… · Web viewshows the velocity-time graph for steel ball A. Figure 2 Explain the shape of the graph in Figure 2. Your account should include • how the velocity and acceleration

AS Extended Writing Practice

272 minutes

266 marks

Q1. A fluorescent light tube contains mercury vapour at low pressure. The tube is coated on the inside, and contains two electrodes.

(a) Explain why the mercury vapour is at a low pressure.

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(b) Explain the purpose of the coating on the inside of the tube.

You may be awarded marks for the quality of written communication in your answer.

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(Total 4 marks)

Q2. Electromagnetic waves and electrons have properties of both particles and waves.Explain what evidence there is to support this statement.Experimental details are not required.

You may be awarded marks for the quality of written communication in your answer.

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Q3. Figure 1 shows the energy level diagram of a hydrogen atom. Its associated spectrum is shown in Figure 2.

The transition labelled A in Figure 1 gives the spectral line labelled B in Figure 2.

Figure 1

Figure 2

hydrogen spectrum showing some of the main spectral lines

(a) (i) Show that the frequency of spectral line B is about 4.6 × 1014 Hz.

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(ii) Calculate the wavelength represented by line B.

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(b) The hydrogen atom is excited and its electron moves to level 4.

(i) How many different wavelengths of electromagnetic radiation may be emitted as the atom returns to its ground state?

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(ii) Calculate the energy, in eV, of the longest wavelength of electromagnetic radiation emitted during this process.

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(c) In a fluorescent tube, explain how the mercury vapour and the coating of its inner surface contribute to the production of visible light. You may be awarded additional marks to those shown in brackets for the quality of written communication in your answer.

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(Total 8 marks)

Q4. (a) When monochromatic light is incident on a metal plate, electrons are emitted only when the frequency of light exceeds a certain frequency.Explain in terms of energy, why this threshold frequency exists and why a photon theory of light provides a better explanation of the photoelectric effect than a wave theory of light.The quality of your written answer will be assessed in this question.

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(b) A gold surface is illuminated with monochromatic ultra violet light of frequency2.10 × 1015 Hz. The maximum kinetic energy of an emitted photoelectron is6.20 × 10–19 J.

Calculate

(i) the energy, in J, of the incident photon,

energy = ..................................J

(ii) the work function of gold,

work function = ....................................(5)

(Total 12 marks)

Q5. When light of a certain frequency is shone on a particular metal surface, electrons are emitted with a range of kinetic energies.

(a) Explain• in terms of photons why electrons are released from the metal surface, and• why the kinetic energy of the emitted electrons varies upto a maximum value.

The quality of your written communication will be assessed in this question.

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(b) The graph below shows how the maximum kinetic energy of the electrons varies with the frequency of the light shining on the metal surface.

(i) On the graph mark the threshold frequency and label it f0.(1)

(ii) On the graph draw a line for a metal which has a higher threshold frequency.(2)

(iii) State what is represented by the gradient of the graph.

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(c) The threshold frequency of a particular metal surface is 5.6 × 1014 Hz. Calculate the maximum kinetic energy of emitted electrons if the frequency of the light striking the metal surface is double the threshold frequency.

answer = .................................. J(3)

(Total 13 marks)

Q6. A student wishes to collect data so he can plot the I-V curve for a semiconductor diode.

(a) (i) Draw a suitable diagram of the circuit that would enable the student to collect this data.

(3)

(ii) Describe the procedure the student would follow in order to obtain an I-V curve for the semiconductor diode.


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(b) The diagram below shows an arrangement of a semiconducting diode and two resistors.

A 12.0 V battery is connected with its positive terminal to A and negative terminal to B.

(i) Calculate the current in the 8.0 Ω resistor

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answer .................................. A(2)

(ii) Calculate the current in the 4.0 Ω resistor if the p.d. across the diode, when in forward bias, is 0.65 V expressing your answer to an appropriate number of significant figures.

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answer ................................... A(3)

(Total 14 marks)

Q7. Electrons with a range of kinetic energies strike atoms of a particular element which are in their ground state. As a result of these collisions photons of various frequencies are emitted by some of the atoms.

(a) Explain what is meant by the ground state of an atom and describe the process that is taking place in the atoms emitting photons.


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(b) The table below shows how the kinetic energies of electrons with different incident energies may change after collisions with atoms.

kinetic energy of electron before collision/eV

kinetic energy of electron after collision/eV

First electron 5.5 5.5

Second electron 9.0 1.0

(i) Explain why one of the electrons loses energy while the other does not.

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(ii) Convert the energy of 9.0 eV into joules

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(iii) Calculate the maximum frequency of the photon emitted when the 9.0 ev electron collides with an atom.

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answer ............................. Hz(3)

(Total 13 marks)

Q8.(a) A sample of conducting putty is rolled into a cylinder which is 6.0 × 10–2 m long and has a radius of 1.2 × 10–2 m.

resistivity of the putty = 4.0 × 10–3 Ωm.

Calculate the resistance between the ends of the cylinder of conducting putty.Your answer should be given to an appropriate number of significant figures.

answer = ...................................... Ω(4)

(b) Given the original cylinder of the conducting putty described in part (a), describe how you would use a voltmeter, ammeter and other standard laboratory equipment to determine a

value for the resistivity of the putty.

Your description should include

• a labelled circuit diagram,• details of the measurements you would make,• an account of how you would use your measurements to determine the result,• details of how to improve the precision of your measurements.


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(Total 12 marks)

Q9. (a) A student wishes to investigate how the resistance of a thermistor changes with temperature.

(i) Draw a labelled diagram of a suitable circuit that would enable the student to measure the resistance of the thermistor.

(2)

(ii) Describe the procedure the student would follow in order to obtain accurate and reliable measurements of the resistance of the thermistor at different temperatures.


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(b) The diagram below shows a thermistor connected in series with a resistor, R, and battery of emf 6.0 V and negligible internal resistance.

When the temperature is 50 °C the resistance of the thermistor is 1.2 kΩ. The voltmeter connected across R reads 1.6V.

(i) Calculate the pd across the thermistor.

answer = ...................................... V(1)

(ii) Calculate the current in the circuit.

answer = ...................................... A(1)

(iii) Calculate the resistance of R quoting your answer to an appropriate number of significant figures.

answer = ..................................... Ω(2)

(c) State and explain the effect on the voltmeter reading if the internal resistance of the battery in the circuit in part (b) was not negligible.

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(Total 14 marks)

Q10. (a) Line spectra were observed before they could be explained by theory. We now know that photons of characteristic frequency are emitted when the vapour of an element is bombarded by energetic electrons. The spectrum of the light emitted contains lines, each of a definite wavelength.

Explain how

• the bombarding electrons cause the atoms of the vapour to emit photons

• the existence of a spectrum consisting of lines of a definite frequency supports the view that atoms have discrete energy levels.


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(b) The ionisation energy of a hydrogen atom is 13.6eV.

(i) State what is meant by the ionisation energy of hydrogen.

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(ii) Express the ionisation energy of hydrogen in joules, giving your answer to anappropriate number of significant figures.

answer = ....................................... J(3)

(Total 11 marks)

Q11. (a) A student is given a piece of metal wire and asked to investigate how the resistance of the wire changes between a temperature of 0 °C and 100 °C.

(i) Draw a labelled diagram of a suitable arrangement that would enable the student to carry out the experiment.

(3)

(ii) Describe the procedure the student would follow in order to obtain accurate and reliable measurements of the resistance of the wire at different temperatures between 0 °C and 100 °C.

The quality of written communication will be assessed in your answer.

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(b) A certain metal has a critical temperature of –268 °C (5 K). Explain what is meant by critical temperature.

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(Total 11 marks)

Q12. (a) An alternating current supply provides an output voltage of 12 V rms at a frequency of 50 Hz. Describe how you would use an oscilloscope to check the accuracy of the rms output voltage and the frequency of the supply.

The quality of your written communication will be assessed in your answer.

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(b) The power supply in part (a) is connected to a 12 V 24 W lamp.

(i) Calculate the rms current in the lamp.

answer = ...................................... A(1)

(ii) Calculate the peak current in the lamp.

answer = ...................................... A(1)

(iii) Calculate the peak power of the lamp.

answer = ...................................... W(2)

(Total 10 marks)

Q13.An experiment can be performed to determine whether a particular component is an ohmic conductor.

(a) State what is meant by an ohmic conductor.

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(b) (i) Draw a suitable circuit diagram for such an experiment.

(2)

(ii) For the circuit diagram you have drawn, describe a suitable experiment. Your account should include details of:

• what measurements you would take

• how you would use your measurements

• how you would reach a conclusion.

The quality of written communication will be assessed in your answer.

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(c) (i) State the principal property of a superconductor.

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(ii) State what is meant by critical temperature.

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(iii) Give one use of a superconductor.

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(Total 12 marks)

Q14.(a) Hadrons and leptons are two groups of particles.Write an account of how particles are placed into one or other of these two groups.Your account should include the following:

• how the type of interaction is used to classify the particles

• examples of each type of particle

• details of any similarities between the two groups

• details of how one group may be further sub-divided.

The quality of your written communication will be assessed in your answer.

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(b) Every type of particle has a corresponding antiparticle.

(i) Give one example of a particle and its corresponding antiparticle.

particle......................................................................................................

antiparticle..................................................................................................(1)

(ii) State one difference between this particle and its antiparticle.

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(Total 8 marks)

Q15. (a) State two requirements for two light sources to be coherent.

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(b) Figure 1

Young’s fringes are produced on the screen from the monochromatic source by the arrangement shown in Figure 1.Explain how this arrangement produces interference fringes on the screen. In your answer, explain why slit S should be narrow and why slits S1 and S2 act as coherent sources.The quality of your written answer will be assessed in this question.

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(c) The pattern on the screen may be represented as a graph of intensity against position on the screen. The central fringe is shown on the graph in Figure 2. Complete this graph to represent the rest of the pattern by drawing on Figure 2.

Figure 2

(2)(Total 10 marks)

Q16. (a) State Hooke’s law.

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(b) A student is asked to measure the mass of a rock sample using a steel spring, standard masses and a metre rule. She measured the unstretched length of the spring and then set up the arrangement shown in the diagram below.

(i) Describe how you would use this arrangement to measure the mass of the rock sample. State the measurements you would make and explain how you would use the measurements to find the mass of the rock sample.The quality of your written communication will be assessed in this question.

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(ii) State and explain one modification you could make to the arrangement in the diagram above to make it more stable.

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(Total 10 marks)

Q17. A student investigated how the extension of a rubber cord varied with the force used to extend it. She measured the extension for successive increases of the force and then for successive decreases. The diagram below shows a graph of her results.

(a) (i) Give a reason why the graph shows the rubber cord does not obey Hooke’s law.

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(ii) Give a reason why the graph shows the rubber cord does not exhibit plastic behaviour.

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(iii) What physical quantity is represented by the area shaded on the graph between the loading curve and the extension axis?

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(b) Describe, with the aid of a diagram, the procedure and the measurements you would make to carry out this investigation.

The quality of your written answer will be assessed in this question.

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(Total 9 marks)

Q18. A steel ball is released from rest above a cylinder of liquid, as shown in Figure 1. The ball

descends vertically in the air then in the liquid until it reaches the bottom of the cylinder.

Figure 1

(a) The vertical distance from the bottom of the ball at the point where it is released to the liquid surface is 0.16 m.

(i) Calculate the time taken, t0, by the ball to fall to the liquid surface from the point where it is released. Give your answer to an appropriate number of significant figures.

answer................................. s(3)

(ii) Calculate the velocity, ν0, of the ball on reaching the liquid.

answer .................................. m s–1

(2)

(b) Figure 2 below shows how the velocity of the ball changed after it was released.

Figure 2

Describe and explain how the acceleration of the ball changed after it entered the liquid until it reached the bottom of the cylinder.


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(Total 11 marks)

Q19. (a) Describe how to obtain, accurately by experiment, the data to determine the Young modulus of a metal wire.

A space is provided for a labelled diagram.


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(b) The diagram below is a plot of some results from an experiment in which a metal wire was stretched.

(i) Draw a best-fit line using the data points.(1)

(ii) Use your line to find the Young modulus of the metal, stating an appropriate unit.

answer = ......................................(4)

(c) After reaching a strain of 7.7 × 10–3, the wire is to be unloaded. On the diagram above, sketch the line you would expect to obtain for this.

(1)(Total 12 marks)

Q20. The figure below shows a gymnast trampolining.

In travelling from her lowest position at A to her highest position at B, her centre of mass rises 4.2 m vertically. Her mass is 55 kg.

(a) Calculate the increase in her gravitational potential energy when she ascends from position A to position B.

answer = ................................... J(2)

(b) The gymnast descends from position B and regains contact with the trampoline when it is in its unstretched position. At this position, her centre of mass is 3.2 m below its position at B.

(i) Calculate her kinetic energy at the instant she touches the unstretched trampoline.

answer = ................................... J(1)

(ii) Calculate her vertical speed at the same instant.

answer = ............................. m s–1

(2)

(c) Draw an arrow on the figure above to show the force exerted on the gymnast by the trampoline when she is in position A.

(1)

(d) As she accelerates upwards again from position A, she is in contact with the trampoline for a further 0.26 s. Calculate the average acceleration she would experience while she is in contact with the trampoline, if she is to reach the same height as before.

answer = ............................. m s–2

(2)

(e) On her next jump the gymnast decides to reach a height above position B. Describe and explain, in terms of energy and work, the transformations that occur as she ascends from her lowest position A until she reaches her new position above B.


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(Total 14 marks)

Q21. The figure below shows a stationary wave on a string. The string is tied onto a thin metal bar at A and fixed at B. A vibration generator causes the bar to oscillate at a chosen frequency.

Explain how a stationary wave is formed. Then describe the key features of the stationary wave shown in the figure above.


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Q22. A scientist is going to use a double-slit arrangement to carry out measurements in order to determine the wavelength of light from a laser.

(a) The scientist has a double slit of known separation. Describe the measurements that need to be taken and explain how they are used to find the wavelength of the light. Discuss any necessary safety precautions and how you would arrange the apparatus to improve accuracy.


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(b) In 1802 Thomas Young used candle light to observe the interference pattern from twonarrow slits acting as coherent light sources.

Explain what is meant by coherent light sources.

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(c) Sketch and label on the diagram below the arrangement that Young would have used toobtain his interference pattern.

(2)

(d) State two differences in the appearance of the pattern obtained with a laser and thatproduced by a white light source such as a candle.

Difference 1 ..................................................................................................

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Difference 2 ..................................................................................................

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(e) Explain how the wave theory of light accounts for the areas on the screen where

theintensity is a minimum.

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(Total 14 marks)

Q23. (a) In an experiment, a narrow beam of white light from a filament lamp is directed at normal incidence at a diffraction grating. Complete the diagram in the figure below to show the light beams transmitted by the grating, showing the zero-order beam and the first-order beams.

(3)

(b) Light from a star is passed through the grating.

Explain how the appearance of the first-order beam can be used to deduce one piece of information about the gases that make up the outer layers of the star.

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(c) In an experiment, a laser is used with a diffraction grating of known number of lines per mm to measure the wavelength of the laser light.

(i) Draw a labelled diagram of a suitable arrangement to carry out this experiment.

(2)

(ii) Describe the necessary procedure in order to obtain an accurate and reliable value for the wavelength of the laser light.Your answer should include details of all the measurements and necessary calculations.The quality of your written communication will be assessed in your answer.

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(Total 13 marks)

Q24.Discuss the formation of stationary waves on a string or rope. Your account should include:

• a labelled diagram of a stationary wave

• the conditions necessary for stationary waves to form

• a definition of the terms node and antinode

• an explanation of how nodes and antinodes form.

The quality of written communication will be assessed in your answer.(Total 6 marks)

Q25.A steel ball has a diameter of 2.2 × 10−2 m.

(a) Calculate the weight of the steel ball. Give your answer to an appropriate number of significant figures.

density of steel = 8100 kg m−3

weight ...........................................N(4)

(b) Figure 1 shows two identical steel balls dropped from rest into containers of oil.

Figure 1

(i) Figure 2 shows the velocity-time graph for steel ball A.

Figure 2

Explain the shape of the graph in Figure 2. Your account should include

• how the velocity and acceleration of the steel ball vary with time

• reference to how Newton’s First and Second laws of motion apply in this situation.

The quality of written communication will be assessed in your answer.(6)

(ii) On Figure 3, sketch the velocity-time graph you would expect to see for steel ball B. Assume air resistance is negligible.

Figure 3

(3)(Total 13 marks)

M1. (a) there must be a large distance between collisions to allow electrons to gain enough energy (1)[or the vapour must not completely absorb the electrons]

1

(b) the mercury vapour emits ultra violet (radiation) (1)

the coating absorbs electromagnetic radiation/light fromthe mercury (1)emits longer wavelengths/lower frequenciesin the visible region (1)

max 3QWC 2

[4]

M2. electrons diffract [or high energy electron scattering] (1)showing wave behaviour (1)

electrons are deflected in electric or magnetic fields (1)showing particle behaviour (1)

interference of electromagnetic waves (1)showing wave behaviour (1)

photoelectric effect (1)showing particle behaviour (1)

max 6QWC 2

[6]

M3. (a) (i) (3.40-1.51 = 1.89)

ΔE= 1.89 × 1.60 × 10–19(J) (1)

(= 3.02 × 10–19(J))

(1)

(=4.56 × 1014Hz)

(ii) (1)

(use of f = 4.6 × 1014 gives λ = 6.5 × 10–7m)3

(b) (i) 6 (wavelengths) (1)

(ii) (1.51–0.85) = 0.66(eV) (1)

2

(c) mercury vapour at low pressure is conducting (1)atoms of mercury are excited by electron impact (1)producing (mainly) ultra violet radiation (1)which is absorbed/ excites the coating (1)which, upon relaxing, produces visible light (1)electrons cascade down energy levels (1)

3[8]

M4. (a) The marking scheme for this part of the question includes anoverall assessment for the quality of written communication.There are no discrete marks for the assessment of writtencommunication but the quality of written communication willbe one of the criteria used to assign the answer to one of three levels.

Level Descriptoran answer will be expected to meet most of the criteria in the

level descriptor

Mark range

Good 3 – answer supported by appropriate range of relevant points

– good use of information or ideas about physics, going beyond those given in the question

– argument well structured with minimal repetition or irrelevant points

– accurate and clear expression of ideas with only minor errors of spelling, punctuation and grammar

6-7

Modest 2 – answer partially supported by relevant points

– good use of information or ideas about physics given in the question but limited beyond this

– the argument shows some attempt at structure

– the ideas are expressed with reasonable clarity but with a few errors of spelling, punctuation and grammar

3-5

Limited 1 – valid points but not clearly linked to an argument structure

– limited use of information or ideas about physics1-2

0

– unstructured

– errors in spelling, punctuation and grammar or lack of fluency

– incorrect, inappropriate or no response

0

physics points:

• the energy of each photon/the light increases with frequency (1)

• electrons need a minimum amount of energy to leave the metal (1)

• the amount of energy required is equal to the work function (1)

• (this suggests) the electrons are given energy in one discrete eventor one electron interacts with one photon (1)

• (so the) light energy is not spread out it is concentrated (intoquanta) (1)

• the electron does not build up energy over time or photoelectricityoccurs immediately light falls on the metal (1)

(b) (i) E = hf = 6.63 × 10–34 × 2.10 × 1015 = 1.39 × 10–18 (J) (1)

(ii) = hf – Ek (1)= 1.39 × 10–18 – 6.20 × 10–19

= 7.72 × 1019 J (1)5

[12]

M5. (a)

QWC descriptor mark range

good-excellent

The candidate provides a comprehensive and logical explanation which recognises that light consists of photons of energy hf and that an electron at or near the metal surface can only gain the energy of a single photon when it interacts with a photon. In addition, the candidate should recognise the significance of the work function (of the metal) in this context in relation to the maximum kinetic energy that an emitted electron can have. The candidate should also provide some indication of why the kinetic energy of an emitted electron may be less than the maximum kinetic energy. Although the term ‘work function’ might not be defined or used, the candidate’s explanation should clearly state that each electron needs a minimum amount of energy to escape from the metal.

5-6

modest-adequat

e

The candidate provides a logical and coherent explanation which includes the key ideas including recognition that light consists of photons of energy hf and that an electron at or near the metal surface can only gain the energy of a single

3-4

photon when it interacts with a photon. In addition, the candidate should be aware that each electron needs a minimum amount of energy to escape from the metal. They should appreciate that the kinetic energy of an emitted electron is equal to the difference between the energy it gains from a photon and the energy it needs (or uses) to escape from the metal. However, the explanation may lack a key element such as why the kinetic energy of the emitted electrons varies.

poor-limited

The candidate provides some correct ideas including recognition that light consists of photons of energy hf and that electrons in the metal (or at its surface) absorb photons and thereby gain energy. Their ideas lack coherence and they fail to recognise or use in their explanation the key idea that one photon is absorbed by one electron.

1-2

The explanations expected in a good answer should include most of the following physics ideas

energy is needed to remove an electron from the surface

work function φ (of the metal) is the minimum energy needed byan electron to escape from the surface

light consists of photons , each of energy E = hf

one photon is absorbed by one electron

an electron can escape (from the surface) if hf > φ

kinetic energy of an emitted electron cannot be greater than hf – φ

an electron below the surface needs to do work/uses energy to reachthe surface

kinetic energy of such an electron will be less than hf – φ

(b) (i)

(ii) parallel line, higher threshold frequency (1)(1)

(iii) Planck’s constant (1)4

(c) (use of hf0 = )

hf = 6.63 × 10–34 × 2 × 5.6 × 1014 (1)

= 3.7(1) × 10–19 J (1)

Ek = 2 × 3.7 × 10–19 – 3.7 × 10–19 = 3.7 × 10–19 J (1)3

[13]

M6. (a) (i)

suitable variable input (variable power supply orvariable resistor) (1)

protective resistor and diode forward biased (1)

correct current and pd measuring devices (1)3

(ii) the mark scheme for this part of the question includes anoverall assessment for the Quality of Written Communication


good-excellent

Uses accurately appropriate grammar, spelling, punctuation and legibility.Uses the most appropriate form and style of writing to give an explanation or to present an argument in a well structured piece of extended writing.[May include bullet points and/or formulae or equations].Answer refers to at least 5 of the relevant points listed below.

5-6

modest-adequate

Only a few errors.Some structure to answer, style acceptable, arguments or explanations partially supported by evidence or examples.Answer refers to at least 3 or the relevant points listed below.

3-4

poor- Several significant errors. 1-2

limited Answer lacking structure, arguments not supported by evidence and contains limited information.Answer refers to no more than 2 of the relevant points.

incorrect,inappropriat

eor no

response

No answer at all or answer refers to unrelated, incorrect or inappropriate physics. 0

The explanation expected in a competent answer shouldinclude a coherent selection of the following physics ideas.

connect circuit up (1)

measure current (I) and pd/voltage (V) (1)

vary resistance/voltage (1)

obtain a range of results (1)

reverse connections to power supply (and repeat) (1)

plot a graph (of pd against current) (1)

mention of significance of 0.6V or disconnect between readingsor change range on meters when doing reverse bias (1)

(b) (i) (use of I = V/R)

I = 12/8 (1)= 1.5A (1)

(ii) I = (12 – 0.65 (1))/4 = 2.8 A (1) sig figs (1)5

[14]

M7. (a) the mark scheme for this part of the question includes an overallassessment for the Quality of Written Communication


good-excellent Uses accurately appropriate grammar, spelling, punctuation and legibility.Uses the most appropriate form and style of writing to give an explanation or to present an argument in a well structured piece of extended writing.[May include formulae or equations].Answer refers to at least 5 of the relevant points listed below.

5-6

modest-adequate Only a few errors.Some structure to answer, style acceptable, arguments or explanations partially supported by evidence or examples.Answer refers to at least 3 or the relevant points listed below.

3-4

poor-limited Several significant errors.Answer lacking structure, arguments not supported by evidence and contains limited information.Answer refers to no more than 2 of the relevant points.

1-2

incorrect,inappropriateor noresponse


The explanation expected in a competent answer should include acoherent selection of the following physics ideas.

electron in atoms can only occupy certain (discrete) energy levels (1)

the ground state is the lowest energy state an electron/atom can occupy (1)

electrons collide with (orbital) electrons (1)

giving the electrons the energy necessary to move to a higher level (1)

electrons later return to a lower level/ground state losing energy (1)

by emitting photons of a characteristic/different/discrete/certain/varying frequencies or ΔE = hf or frequency depends on energydifference (1)

(b) (i) the 5.5 eV electron does not have enough energy to excitean (orbital) electron/atom (1)

the 9.0 eV electron provide enough energy to excite an (orbital)electron/atom (1)

(ii) energy = 9.0 × 1.6 × 10–19 (1) = 1.44 × 10–18 (J) (1)

(iii) E = 1.44 × 10–18 – 1.6 × 10–19 = 1.28 × 10–18 (1) (J)

6.63 × 10–34 × f = 1.28 × 10–18 (1)

f = 1.28 × 10–18/6.63 × 10–34 = 1.9 × 1015 Hz (1)7

[13]

M8.(a) (use of R = ρl/A)

R = 4.0 × 10–3 × 0.060 (1)/(π × 0.0122) (1)

R = 0.53 (Ω) (1)

2 significant figures (1)4

(b) the mark scheme for this part of the question includes an overallassessment for the Quality of Written Communication

circuit must include:

voltmeter and ammeter connected correctly (1)

power supply with means of varying current (1)2


good-excellent

(i) Uses accurately appropriate grammar, spelling, punctuation and legibility.

(ii) Uses the most appropriate form and style of writing to give an explanation or to present an argument in a well structured piece of extended writing.[may include bullet points and/or formulae or equations]

An excellent candidate will have a working circuit diagram with correct description of measurements (including range of results) and processing. An excellent candidate uses a range of results and finds a mean value or uses a graphical method, eg I-V characteristics. They also mention precision eg use of vernier callipers.

5-6

modest-adequate

(i) Only a few errors.

(ii) Some structure to answer, style acceptable, arguments or explanations partially supported by evidence or examples.

An adequate candidate will have a working circuit and a description with only a few errors, eg do not consider precision. They have not taken a range of results and fail to realise that the diameter needs to be measured in several places.

3-4

poor-limited

(i) Several significant errors.

(ii) Answer lacking structure, arguments not supported by evidence and contains limited information.

Several significant errors, eg important measurement missed, incorrect circuit, no awareness of how to calculate resistivity.

1-2

incorrect, inappropriate

or no response

0

The explanation expected in a good answer should include a coherentaccount of the procedure and include most of the following points.

• length with a ruler

• thickness/diameter with vernier callipers/micrometer

• measure voltage

• measure current

• calculate resistance

• use of graph, eg I-V or resistance against length

• use of diameter to calculate cross-sectional area

• mention of precision, eg vernier callipers or full scale readingsfor V and I

• flat metal electrodes at each end to improve connection6

[12]

M9. (a) (i) working circuit including power supply and thermistor(correct symbol) (1)

voltmeter and ammeter or ohm meter (1)2

(ii) The candidate’s writing should be legible and the spelling,punctuation and grammar should be sufficiently accuratefor the meaning to be clear.

The candidate’s answer will be assessed holistically. The answerwill be assigned to one of three levels according to the followingcriteria.

High Level (Good to excellent): 5 or 6 marks

The information conveyed by the answer is clearly organised,logical and coherent, using appropriate specialist vocabularycorrectly. The form and style of writing is appropriate toanswer the question.The candidate states that the thermistor is connected in asuitable circuit with voltmeter and ammeter or ohmmeter.The candidate gives details of how the thermistor is heatedin a beaker of water or a water bath and a thermometer is usedto measure the temperature at small regular intervals.The candidate states that the resistance is found at varioustemperatures either directly with an ohmmeter or by dividingvoltage by current. The candidate may mention that the watermust be stirred to ensure that the thermistor is at thetemperature measured by the thermometer.The candidate may give some indication of the range oftemperatures to be used.The candidate may refer to repetition of whole experiment.The candidate may plot a graph of resistance against

temperature.The candidate may use a digital thermometer.

Intermediate Level (Modest to adequate): 3 or 4 marks

The information conveyed by the answer may be less wellorganised and not fully coherent. There is less use of specialistvocabulary, or specialist vocabulary may be used incorrectly.The form and style of writing is less appropriate.

The candidate states that the thermistor is connected in asuitable circuit with voltmeter and ammeter or ohmmeter.The candidate gives details of how the thermistor is heatedin a beaker of water and a thermometer is used to measurethe temperature.The candidate states that the resistance is found at varioustemperatures either directly with an ohmmeter or by dividingvoltage by current.

Low Level (Poor to limited): 1 or 2 marks

The information conveyed by the answer is poorly organisedand may not be relevant or coherent. There is little correctuse of specialist vocabulary.The form and style of writing may be only partly appropriate.

The candidate changes temperature at least once andmeasures V and I or R.

The explanation expected in a competent answershould include a coherent selection of the followingpoints concerning the physical principles involved andtheir consequences in this case.

Max 6

(b) (i) pd = 6.0 – 1.6 = 4.4 (V) (1)1

(ii) current = 4.4/1200 = 3.7 × 10–3 (A) (1) (not 3.6)1

(iii) resistance = 1.6/3.7 × 10–3 = 440 or 430 (Ω) (1)

2 sfs (1)2

(c) less current now flows or terminal pd/voltage lower (1)(or voltage across cell/external circuit is lower)

(hence) pd/voltage across resistor will decrease (1)2

[14]

M10. (a) The candidate’s writing should be legible and the spelling,

punctuation and grammar should be sufficiently accuratefor the meaning to be clear.

The candidate’s answer will be assessed holistically. Theanswer will be assigned to one of three levels according to thefollowing criteria.


The information conveyed by the answer is clearly organised,logical and coherent, using appropriate specialist vocabularycorrectly. The form and style of writing is appropriate to answerthe question.

The candidate provides a comprehensive and coherentdescription which includes a clear explanation of constantenergy level differences and how electrons can be excitedby electron collisions. The link between the energy of a photonand its frequency should be clear. The description shouldinclude a clear explanation of the reason atoms of a givenelement emit photons of a characteristic frequency or thereis a clear link between constant energy differences and photonfrequency/wavelength (eg E=hf).The candidate should relate the energy difference betweenlevels to the energy of emitted photons and state the energydifference is fixed/constant.



The candidate provides an explanation of energy levels andhow excitation takes place by electron collision with atomic/orbital electrons. The candidate explains how anorbital/atomic electron loses energy by emitting a photon.


The information conveyed by the answer is poorly organisedand may not be relevant or coherent. There is little correctuse of specialist vocabulary.

The form and style of writing may be only partly appropriate.Some mention of energy levels and the idea of excitation ofelectron. Talk about excitation of atom instead of electron limitsthe mark to 1.

Incorrect, inappropriate of no response: 0 marks

No answer or answer refers to unrelated, incorrect or inappropriate physics.

The explanation expected in a competent answer should include acoherent account of the significance of discrete energy levelsand how the bombardment of atoms by electrons can lead toexcitation and the subsequent emission of photons of a characteristicfrequency.

electrons bombard atoms of vapour and give energy to electrons in atom

electrons move to a higher energy level

electrons are excited

excited electrons move down to lower energy levels losing energy byemitting photons

photons have energy hf

photons of characteristic frequencies emitted from atoms of aparticular element

this is because atoms have discrete energy levels which areassociated with particular energy values

max 6

(b) (i) energy required to (completely) remove an electronfrom atom/hydrogen

ground state/lowest energy level 2

(ii) 13.6 × 1.6 × 10–19 = 2.18 × 10–18 (J) 3 sfs 3

[11]

M11. (a) (i) circuit with ammeter and voltmeter correct or ohmmeter

some means of heating eg water bath

thermometer in water bath 3

(ii) The candidate’s writing should be legible and the spelling, punctuation and grammar should be sufficiently accurate for the meaning to be clear.

The candidate’s answer will be assessed holistically. The answer will be assigned to one of three levels according to the following criteria.


The information conveyed by the answer is clearly organised, logical and coherent, using appropriate specialist vocabulary correctly. The form and style of writing is appropriate to answer the question.

The candidate states that resistance is measured using an ohmmeter or voltmeter ammeter method. The wire is heated in a beaker of water and the temperature measured with a thermometer. Ice is added to the water and the water is stirred as the water is heated. Details of how resistance is calculated and how results are presented e.g. graph of resistivity against temperature.


The information conveyed by the answer may be less well organised and not fully coherent. There is less use of specialist vocabulary, or specialist vocabulary may be used incorrectly. The form and style of writing is less appropriate.

The candidate states that resistance is measured using an ohmmeter or voltmeter ammeter method. The wire is heated in a beaker of water and the temperature measured with a thermometer. Ice is added to the water. Details of how resistance is calculated.


The information conveyed by the answer is poorly organised and may not be relevant or coherent. There is little correct use of specialist vocabulary. The form and style of writing may be only partly appropriate.

The candidate states that resistance is measured using an ohmmeter or voltmeter ammeter method. The wire is heated in a beaker of water and the temperature measured with a thermometer.

The explanation expected in a competent answer should include a coherent selection of the following points concerning the physical principles involved and their consequences in this case.

• resistance measured calculated

• water bath used

• ice added to water

• water stirred

• temperature measured with thermometer

• resistance calculated

• graph drawn6

(b) the temperature at or below which a material

becomes a superconductor or has zero resistance/resistivity 2

[11]

M12. (a) The candidate’s writing should be legible and the spelling, punctuation and grammar should be sufficiently accurate for the meaning to be clear.

The candidate’s answer will be assessed holistically. The answer will be assigned to one

of three levels according to the following criteria.



The candidate states that the power supply is connected to the input of the oscilloscope. The time base is switched off and the y gain adjusted until a complete vertical line is seen on the screen. The length of the line is measured and this is converted to peak to peak voltage using the calibration. The peak voltage is divided by root two to get the rms voltage and this is compared with the stated value. The time base is now switched on and adjusted until a minimum of one cycle is seen on the screen. The length of one cycle is measured and this is converted to time using the time base setting. Frequency is the reciprocal of this time.


The information conveyed by the answer may be less well organised and not fully coherent. There is less use of specialist vocabulary, or specialist vocabulary may be used incorrectly. The form and style of writing is less appropriate.

The candidate states that the power supply is connected to the input of the oscilloscope. The y gain adjusted. The length of the line/height of peak is measured. The peak voltage is divided by root two to get the rms voltage. The time base is now switched on and adjusted until a minimum of one cycle is seen on the screen. The length of one cycle is measured and this is converted to time using the time base setting.


The information conveyed by the answer is poorly organised and may not be relevant or coherent. There is little correct use of specialist vocabulary. The form and style of writing may be only partly appropriate.

The candidate states that the power supply is connected to the input of the oscilloscope. The length of the line/height of peak is measured. The time base is now switched on and adjusted until a minimum of one cycle is seen on the screen. The length of one cycle is measured and this is converted to time.


• power supply connected to oscilloscope input

• time base initially switched off

• y gain adjusted to get as long a line as possible

• length of line used to find peak to peak voltage

• rms voltage found

• time base switched on and adjusted to get several cycles on the screen

• use the time base setting to find period

• use period to find frequency

• compare vales with stated values6

(b) (i) (use of P = IV)

I = 24/12 = 2.0 (A) 1

(ii) peak current = √2 × 2.0 = 2.8 (A) 1

(iii) peak power = √2 × 12 × √2 × 2.0 = 48 (W) 2

[10]

M13.(a) a component with constant resistance OR V ∝ I 1

(b) (i) circuit using correct symbols with means of varying current / voltage correct voltmeter and ammeter

ignore symbol for componentunless it is a variable resistor

2

(ii) The candidate’s writing should be legible and the spelling, punctuation and grammar should be sufficiently accurate for the meaning to be clear.The candidate’s answer will be assessed holistically. The answer will be assigned to one of three levels according to the following criteria.

High Level (Good to excellent): 5 or 6 marksThe information conveyed by the answer is clearly organised, logical and coherent, using appropriate specialist vocabulary correctly. The form and style of writing is appropriate to answer the question.

Candidate draws an appropriate circuit diagram with correctly positioned ammeter and voltmeters. Candidate has a means of varying the current. Sets current to different values and measures pd. Mentions wide range. Has a sensible way of varying current (e.g. variable resistor / potential divider). Plots a graph of pd against current. Relates constant gradient to a constant resistance.

Level 5 / 6meaning of line through originreverse current readingssuitable range with suggested values

Intermediate Level (Modest to adequate): 3 or 4 marksThe information conveyed by the answer may be less well organised and not fully coherent. There is less use of

specialist vocabulary, or specialist vocabulary may be used incorrectly. The form and style of writing is less appropriate.Candidate draws an appropriate circuit diagram with correctly positioned ammeter and voltmeters. Candidate has a means of varying the current. Varies current and measures pd. Plots a graph of pd against current. Relates constant gradient to a constant resistance.

Level 3 / 4Draw best fit line or state R constantRelate straight line on graph to ohmic conductor

Low Level (Poor to limited): 1 or 2 marksThe information conveyed by the answer is poorly organised and may not be relevant or coherent. There is little correct use of specialist vocabulary. The form and style of writing may be only partly appropriate.

The candidate measures resistance at least twice to see if constant. Has some means of varying current.

Level 1 / 2Take several readings of V and I and plot graph or calculate R


method for varying currentcurrent varied in regular stepspd and current measureresistance calculatedgraph drawnsignificance of gradient of the graph discussed

6

(c) (i) a material with zero resistivity / resistance not negligible

1

(ii) material becomes superconducting at / below critical temperature accept reverse argument

1

(iii) any correct usage e.g. powerful magnets, mri, maglev trains / bullet train / (high power) transmission lines / particle accelerators / LHC

1[12]

M14.(a) The candidate’s writing should be legible and the spelling, punctuation and grammar should be sufficiently accurate for the meaning to be clear.The candidate’s answer will be assessed holistically. The answer will be assigned to one of three levels according to the following criteria.


Top BandBoth have rest massMention electromagnetic interaction Correct quark structure of mesons and baryonsBoth hadrons and leptons interact/decay through weak interactionFor 6 marks must have last two points

Candidate gives correct examples of hadrons and leptons. Identifies the differences between hadrons and leptons (hadrons affected by strong nuclear reaction and are made of quarks). Leptons are fundamental and do not experience the strong nuclear reaction. Hadrons are divided into baryons and mesons. Baryons three quarks, mesons quark anti-quark pair. Similarities between groups all experience weak interaction and if charged the electromagnetic interaction. All have rest mass.

Intermediate Level (Modest to adequate): 3 or 4 marksThe information conveyed by the answer may be less well organised and not fully coherent. There is less use of specialist vocabulary, or specialist vocabulary may be used incorrectly. The form and style of writing is less appropriate.

Middle bandOnly hadrons experience strong nuclear interaction (need this to get in middle band)Hadrons are mesons or baryons. Examples of each

Candidate gives correct examples of hadrons and leptons. Identifies one difference between hadrons and leptons (e.g. hadrons affected by strong nuclear reaction or are made of quarks). Leptons are fundamental. Hadrons are divided into baryons and mesons.


Lower band1 or 2 correct facts about hadrons leptons eg Leptons are fundamental / hadrons made of quarks

Identifies two correct properties of hadrons and leptons.

The explanation expected in a competent answer should include a coherent selection of the following points concerning the physical principles involved and their consequences in this case.example of hadron and leptonmention of strong interactionmention of quark structure hadronsleptons are fundamentalidentify baryons and mesonsgives quark structure of baryons and mesonssimilarities e.g. all have rest massall affected by weak interactionif charged both experience electromagnetic interaction

6

(b) (i) a correct example of particle e.g. electronand correct example of antiparticle e.g. positron

Allow correct symbolsAllow antielectron for positronAlso allow pi zero and gamma

1

(ii) correct difference e.g. opposite charge/other named quantum number must be consistent with (i)

1[8]

M15. (a) same wavelength or frequency (1)

same phase or constant phase difference (1)2

(b) The marking scheme for this part of the question includes an overallassessment for the Quality of Written Communication (QWC).There are no discrete marks for the assessment of QWC but thecandidates’ QWC in this answer will be one of the criteria usedto assign a level and award the marks for this part of the question.

Level Descriptoran answer will be expected to meet most of the criteria in the

level descriptor

Mark range

Good 3 – answer includes a good attempt at the explanations required

– answer makes good use of physics ideas including knowledge beyond that given in the question

– explanation well structured with minimal repetition or irrelevant points and uses appropriate scientific language

– accurate and logical expression of ideas with only minor/occasional errors of grammar, punctuation and spelling

5-6

Modest 2 – answer includes some attempts at the explanations required

– answer makes use of physics ideas referred to in the question but is limited to these

– explanation has some structure but may not be complete

– explanation has reasonable clarity but has a few errors of grammar and/or punctuation and spelling

3-4

Limited 1 – answer includes some valid ideas but these are not organised in a logical or clear explanation

– answer lacks structure

– several errors in grammar, punctuation and spelling

1-2

0 – incorrect, inappropriate or no response 0

the explanations expected in a competent answer should include a coherent selection of the following physics ideas:

• narrow single slit gives wide diffraction

• to ensure that both S1 and S2 are illuminated

• slit S acts as a point source

• narrow single slit ensures it provides coherent sources of light atS1 and S2

• S1 and S2 are illuminated by same source giving same wavelength

• paths to S1 and S2 are of constant length giving constant phasedifference or SS1 and

SS2 so waves are in phase

• light is diffracted as it passes through S1 and S2 and the diffractedwaves overlap and interfere

• where the path lengths from S1 and S2 to the screen differ bywhole numbers, n of wavelengths, constructive interferenceoccurs producing a bright fringe on the screen

• where the path lengths differ by (n + ½) wavelengths, destructiveinterference occurs producing a dark fringe on the screen

(c) graph to show: maxima of similar intensity to central maximum (1) (or some decrease in intensity outwards from centre)

all fringes same width as central fringe (1)2

[10]

M16. (a) the force (needed to stretch a spring is directly) is proportionalto the extension (of the spring from its natural length) or equationwith all terms defined (1)

up to the limit of proportionally (1)2

(b) (i) The explanations expected in a competent answer shouldinclude a coherent account of the following measurementsand their use

measurements

(use a metre rule to) measure the length of the spring (1)

when it supports a standard mass (or known) mass (m) andwhen it supports the rock sample

repeat for different (standard) masses

accuracy – use a set square or other suitable method tomeasure the position of the lower end of the spring againstthe (vertical) mm rule or method to reduce parallax

use of measurements

either

plot graph of mass against length (or extension) (1)

read off mass corresponding to length (or extension) dueto the sample (1)

or

the extension of the spring = length – unstretched length (1)

(ii) use a (G) clamp (or suitable heavy weight) to fix/clamp thebase of the stand to the table (1)

clamp (or weight) provides an anticlockwise moment (aboutthe edge of the stand greater than the moment of the objecton the spring)/ counterbalances (the load) (1)

or adjust the stand so the spring is nearer to it (1)

so the moment of the load is reduced (and is less likely toovercome the anticlockwise moment of the base of the standabout the edge of the stand) (1)

or turn the base of the stand/rotate the boss by 180° (1)

so the weight of the load acts through the base (1)2

[10]

M17. (a) (i) the lines are not straight (owtte) (1)

(ii) there is no permanent extension (1)(or the overall/final extension is zero or the unloading curvereturns to zero extension)

(iii) (area represents) work done (on or energy transfer to therubber cord) or energy (stored) (1) not heat/thermal energy

3



good-excellent

The candidate provides a comprehensive and coherent description which includes nearly all the necessary procedures and measurements in a logical order. The descriptions should show awareness of how to apply a variable force. They should know that measurements are to be made as the force is increased then as it is decreased. In addition, they should know how to

5-6

calculate/measure the extension of the cord. At least five different masses/’large number’ of masses are used. Minimum 7 masses to reach 6 marks. The diagram should be detailed.

modest-adequate

The description should include most of the necessary procedures including how to apply a variable force and should include the necessary measurements. They may not have described the procedures in a logical order. They may not appreciate that measurements are also to be made as the cord is unloaded. They should know that the extensionof the cord must be found and name a suitable measuring instrument (or seen in diagram – label need not be seen)/how to calculate. The diagram may lack some detail.

3-4

poor-limited

The candidate knows that the extension or cord length is to be measured for different forces – may be apparent from the diagram. They may not appreciate that measurements are also to be made as the cord is unloaded.They may not state how to calculate the extension of the cord. The diagram may not have been drawn.

1-2

incorrect,inappropriat

eor no

response


The explanation expected in a competent answer should includea coherent selection of the following physics ideas.

diagram showing rubber cord fixed at one end supporting a weightat the other end or pulled by a force (1)

means of applying variable force drawn or described (eg use of standardmasses or a newtonmeter) (1)

means of measuring cord drawn or described (1)

procedure

measured force applied ( or known weights used) (1)

cord extension measured or calculated (1)

repeat for increasing then decreasing length (or force/weight) (1)

extension calculated from cord length – initial length (1)[9]

M18. (a) (i) (u = 0, s = 0.16 m, a = 9.8(1) m s–2)(rearranging s = ut + ½ at2 with u = 0 gives)

t2 = or v2 = u2 + 2gs or 0.16 = 1/2 × 9.81 t2

or t0 = (1) = 0.1804 or 0.1806 or 0.181 etc (1)

(s) 2 sf only (1)

(ii) (v0 = u + at0 =) 0 + 9.81 × 0.18 ecf (a) (i) or v2 = 2 × 9.81 × 0.16 (1)= 1.8 or 1.77 (m s–1) (1)

5



good-excellent The candidate provides a correct description of the motion of the ball including its deceleration in the fluid decreasingand becoming zero (or attaining constant velocity). They should give a comprehensive and coherent explanation which includes nearly all the necessary principles in a logical order. In their explanation, the candidate should refer to the forces including their directions acting on the ball, why theresistive force decreases and why the acceleration becomes zero.

5-6

modest-adequate The description should refer to the ball decelerating in the fluid until it becomes zero or attains constant velocity. Their explanation should be fairly coherent although it may not be comprehensive and may focus only on the forces acting when the ball attains constant velocity - balanced forces - or on the reason for the initial deceleration.

3-4

poor-limited The candidate knows that the ball decelerates (acceleration with direction) or is acted on by an upward force (as well as the force of gravity). Their explanation of why the ball attains constant velocity may be absent.

May be sketchy and lacks key considerations. They may not appreciate that the two forces are equal and opposite when the ball is moving at constant velocity.

1-2

incorrect,inappropriateor noresponse


The explanation expected in a competent answer should include acoherent selection of the following physics ideas.

The ball decelerates/slows down in the fluid (1) if acceleration is usedthe direction must be specified

• because a force due to fluid friction/resistance/viscosity acts(upwards) on the ball (1)

• (and) the force due to the fluid is greater than the weightof the ball (1)

• resistive force is upwards (1)

• resistive force decreases (1)

The deceleration decreases (to zero) (1)

• because the force due to fluid friction/resistance/viscositydecreases as the ball’s speed decreases (1)

• until it is equal (and opposite) to the weight of the ball (1)(or the resultant force is zero)

• gradient of graph gives the acceleration and the ball movesat constant/terminal velocity/a = 0 (1)

[11]

M19. (a) the mark scheme for this part of the question includes an overallassessment for the Quality of Written Communication


good-excellent

(i) Uses accurately appropriate grammar, spelling, punctuation and legibility.

(ii) Uses the most appropriate form and style of writing to give an explanation or to present an argument in a well structured piece of extended writing.[may include bullet points and/or formulae or equations]

Physics: describes a workable account of making most measurements accurately.

For 6 marks: complete description of the measurements required + how to find the extension +

5-6

instruments needed + at least 2 accuracy points

For 5 marks: all 4 quantities measured including varyingload + 2 instruments, 2 accuracy points.

modest-adequate

(i) Only a few errors.

(ii) Some structure to answer, style acceptable, arguments or explanations partially supported by evidence or examples.

Physics: describes a workable account of making all or most of the measurements and has some correct awareness of at least one accurate measurement.

For 4 marks: all 4 quantities measured including varyingload + 2 instruments mentioned + 1 accuracy point.

For 3 marks: 3 quantities (load, extension, diameter orcross-sectional area) may only omit original length + 1 instrument + 1 accuracy point.

3-4

poor-limited

(i) Several significant errors.

(ii) Answer lacking structure, arguments not supported by evidence and contains limited information.

Physics: unable to give a workable account but can describe some of the measurements.

For 2 marks: load or mass + measure extension + one instrument mentioned.

For 1 mark: applying a single load/mass + one other quantity or one instrument named or shown.

1-2

incorrect, inappropriat

e or no response

0

Quantities to be measured

• describe/show means of applying a load/force to a wire

• measure original length

• measure extension

• measure diameter

• extension = extension length ‘ original length (needed for six marks)

Measuring instruments

• use of rule/ruler/tape measure

• measure diameter with micrometer

• use of travelling microscope to measure extension, or extensionof wire measured with vernier scale for Searle’s apparatus

Accuracy

• varying load/mass

• repeat readings (of length or extension)

• diameter measured in several places

• Searle’s ‘control’ wire negating effect of temperature change

• change in diameter monitored (with micrometer)

• original length of wire ≥ 1.0 m

Additional creditworthy point

• explain how cross-sectional area is found using A = π (D/2)2

• showing how Young modulus is found is regarded as neutral6

(b) (i) good straight line through origin (within one square) upto stress = 5.1 × 107 and line that lies close to data pointsthereafter (1)

1

(ii) evidence of use of gradient or stress/strain (1)

Δ strain used ≥ 3.2 (× 10–3) for correct gradient calculation (1)

1.0 ± 0.05 × 1010 (1) (0.95 to 1.05) allow 1 sf

ecf form their line – may gain full marks

Pa or N m–2 or N/m2 only (1)4

(c) originates at last point + parallel to their first line + straight + touchesx axis (1)1

[12]

M20. (a) (ΔEp = mgΔh) = 55 × 9.8(1) × 4.2 (1)

= 2300 (J) (1) (2266.1)2

(b) (i) (Ek = 3.2/4.2 × 2264 or uses suitable kinematics equation)= 1700(J) (1) (= 1724.8 = 1720)

1

ecf (a)

(ii) (Ek = + mv2 = 1724.8) v = = √62.72ecf (b) (i)

or use of v2 = 2as (1)

= 7.9 m s–1 (1) (= 7.9196)2

(c) one arrow, vertical, upward pointing, starts on soles of feet (1)1

(d) (use of α = gives) = (1)or ecf (b) (ii)/0.26

= 30 (m s–2) (1) (30.46)

or use α = of or α = (1)allow incorrect values of s here

= 29.6 or 31.4 respectively (1)2

(e) The candidate’s writing should be legible and the spelling,punctuation and grammar should be sufficiently accurate for themeaning to be clear.

The candidate’s answer will be assessed holistically. The answerwill be assigned to one of three levels according to the following criteria.


The information conveyed by the answer is clearly organised,logical and coherent, using appropriate specialist vocabularycorrectly. The form and style of writing is appropriate to answerthe question.

Candidate must state that:

• (elastic potential) energy is transformed to kinetic ortrampoline does work (on gymnast)

• (KE) is transformed into (gravitational) potential energy

• (the gymnast) must ‘jump’/bend knees/do work/‘use’chemical energy/supply energy (to increase height)

For 6 marks, must also state that (the gymnast) must overcomeresistive forces (drag/heat loss/reference to energy ‘lost’ intrampoline, etc)



Candidate must state one from:

• chemical energy (transferred) to elastic, kinetic orgravitational energy

• PE (from trampoline) to KE (of gymnast)

• KE (gymnast) to (G)PE (gymnast)

and one of the following:

• work is done by the trampoline (on the gymnast)

• that work is done on the trampoline (by the gymnast)

• work done against resistive forces

• (additional) energy input required (to achieve additionalheight)


The information conveyed by the answer is poorly organisedand may not be relevant or coherent. There is little correct useof specialist vocabulary. The form and style of writing may beonly partly appropriate.

Candidate must

• give one relevant energy gain or loss in the system orstate that energy is input to reach greater height

For two marks, a relevant energy transformation must begiven or one further marking point:

• (to reach the same height) the gymnast must do workin order to replace the energy wasted as the springsand the trampoline (rubber) unload (contract)

• to reach a greater height, the gymnast must do additionalwork by (bending and) extending her legs (jumping) asthe trampoline moves upwards

• the additional downward force keeps the trampolineextended for longer, thus

increasing the impulse

• correct reference to law of energy conservationmax 6

[14]

M21. The candidate’s writing should be legible and the spelling, punctuationand grammar should be sufficiently accurate for the meaning to be clear.

The candidate’s answer will be assessed holistically. The answer will beassigned to one of the three levels according to the following criteria.

High Level (good to excellent) 5 or 6 marks

The information conveyed by the answer is clearly organised, logical andcoherent, using appropriate specialist vocabulary correctly. The form andstyle of writing is appropriate to answer the question.

Mentions waves travelling in opposite directions or waves of samefrequency (and amplitude) and superpose or interfere or add together.

Intermediate Level (modest to adequate) 3 or 4 marks

The information conveyed by the answer may be less well organised andnot fully coherent. There is less use of specialist vocabulary, or specialistvocabulary may be used incorrectly. The form and style of writing is lessappropriate.

Mentions waves travelling in opposite directions (accept ‘waves reflect/rebound back or from clamp’) or superposition/addition/interference ofwaves or waves of same frequency/wavelength.

Low Level (poor to limited) 1 or 2 marks

The information conveyed by the answer is poorly organised and may notbe relevant or coherent. There is little correct use of specialist vocabulary.The form and style of writing may only be partly appropriate.

One correct key feature or one relevant remark regarding formation given.

The explanation expected in a competent answer should include acoherent account of the following points concerning the physicalprinciples involved and their consequences in this case.

• 4 nodes where there is no movement/zero amplitude

• 3 antinodes where amplitude is maximum

• wavelength 0.80 m

• end antinodes in phase/middle and ends in antiphase

• between node and antinode, amplitude of oscillation increases

• waves reflect off the clamp (and the rod)

• waves travelling in opposite directions superpose/add/interfere

• wave have same wavelength and frequency (similar amplitude)

• always cancellation at nodes/always constructive superposition at antinodes

• energy is not transferred along string[6]

M22. (a) The candidate’s writing should be legible and the spelling, punctuation and grammar should be sufficiently accurate for the meaning to be clear.




The candidate provides a comprehensive and coherent description which includes; fringe spacing/separation w and distance D

measured with one instrument named, uses λ = to obtain value for λ,measures distance between several maxima and includes a valid point about safety.


The information conveyed by the answer may be less well organisedand not fully coherent. There is less use of specialist vocabulary, or specialist vocabulary may be used incorrectly. The form and style of writing is less appropriate.

The candidate provides an adequate explanation that lacks some of the essential points. The candidate is expected to include; w or ‘fringes’ measured or uses

λ = to obtain value for λ. They include one accuracy point or a valid point about safety.


The information conveyed by the answer is poorly organised and may not be relevant or coherent. There is little correct use of specialist vocabulary. The form and style of writing

may be only partly appropriate.

The candidate provides a limited explanation with no more than one or two valid points.



The explanation expected in a competent answer should include a coherent selection of the following points.

Measurements

• suitable measuring instrument for w

• suitable measuring instrument for D

Finding the wavelength

• uses λ = to obtain value for λ.• explains graphical approach

Accuracy

• several fringe spaces measured

• centres of fringes used

• five or more fringes/four fringe spaces measured

• large value of D

• D greater than or equal to 2 m

• dark room

• repeat measurements

• vernier calliper for w (not ‘calliper’, not micrometer)

• graphical method varying D and measuring w

• other valid accuracy point

Safety

• avoid shining laser at (or near) a person

• laser safety goggles

• avoid reflections

• warning sign or light

Max 6

(b) (light from both sources has) constant phase relationship / difference

‘in phase’ or ’same wavelength’ or ‘same frequency’ is one mark2

(c) single slit then double slits to the right

single slit and double slits labelled 2

(d)

if candidate refers to white light Young’s fringes with white light;

orif candidate refers to the laser;

contain (different) colours or central white fringe

monochromatic/one colour

less intense more intense

maxima wider/minima narrower ormax or min closer together for white light compared to a red laser

maxima narrower/minima wider ormax or min further apart for a redlaser

fringes/lines/bands etc compared to ‘dots’

‘dots’ for laser compared to ‘bands’ etc

2

from each row, one only max 2

(e) cancellation / waves cancel / destructive interference/destructive superposition

(light from one slit meets light from the other) in antiphase (180 out of phase) or a path difference of ((n+) ½) λ

2[14]

M23. (a) max three from

central maximum shown

two equally spaced first order maxima

central and one first order labelled correctly

central white maximum

indication of spectra/colours in at least one first order beam

at least one first order beam labelled with violet (indigo or blue) closest to thecentre or red furthest

3

(b) dark/black lines or absorption spectrum or Fraunhofer lines

(reveal the) composition (of the star’s atmosphere)

accept dark ‘bands’

accept atoms or elements in the star

or the peak of intensity

(is related to) the temperature

or Doppler (blue or red) shift

(speed of) rotation or speed of star (relative to Earth) 2

(c) (i) grating and screen shown with both labelled

laser or laser beam labelled 2

(ii) The candidate’s writing should be legible and the spelling, punctuation and grammar should be sufficiently accurate for the meaning to be clear.



The information conveyed by the answer is clearly organised, logical and coherent, using appropriate specialist vocabulary correctly. The form and styleof writing is appropriate to answer the question.

• correct use of (n)λ = d sin θ

• and measure appropriate angle (eg ‘to first order beam’ is the minimum required)

• and method to measure angle (eg tan θ = x/D, spectrometer, accept protractor)

• and at least one way of improving accuracy/reliability

• for full marks: also explain how d is calculated, eg d = 1/ lines per mm (× 103)


The information conveyed by the answer may be less well organised and notfully

coherent. There is less use of specialist vocabulary, or specialistvocabulary may be used incorrectly. The form and style of writing is lessappropriate.

• use of (n)λ = d sin θ

• and measure appropriate angle (eg ‘to first order beam’ is the minimum required)

• and method of measurement of θ (eg tan θ = x/D, spectrometer, accept protractor) or at least one way of improving accuracy/reliability


The information conveyed by the answer is poorly organised and may not berelevant or coherent. There is little correct use of specialist vocabulary. The formand style of writing may be only partly appropriate.

• use of (n)λ = d sin θ

• or measure appropriate angle (eg ‘to first order beam’ is the minimum required)

• or at least one way of improving accuracy/reliability



The explanation expected in a competent answer should include

Accuracy/reliability points

• measure between more than one order (eg 2 θ)

• measure θ for different orders (for average λ not average angle)

• check or repeat/repeat for different distances (D)

• use of spectrometer

• use large distance to screen (D)

• protractor with 0.5 degree (or less) intervals

• graphical method: plot sin θ against n (gradient = λ/d)6

[13]

M24.Good / Excellent

The candidate’s writing should be legible and the spelling, punctuation and grammar should be sufficiently accurate for the meaning to be clear.The candidate’s answer will be assessed holistically. The answer will be assigned to one of three levels according to the following criteria.


can say disturbance, amplitude or displacement

Mentions:

• (1) waves (meet when) travelling in opposite directions / cross/ wave meets a reflected wave / etc

• (2) same wavelength (or frequency)

• (3) node – point of minimum or no disturbance

• (4) antinode – point of maximum disturbance / maximum displacement/amplitude occurs

• (5) node - two waves (always) cancel / destructive interference / 180o phase difference (between displacements of the two waves at the node)

• (6) antinode – reinforcement / constructive interference occurs / (displacements) in phase

• (7) mention of superposition of the two waves

5 marks: points (1) AND (2) with three points from (3), (4), (5), (6) or (7)

for 6 marks: points (1) to (6) must be seenlabelled diagram can provide supporting evidence but labels: ‘node’ / ‘antinode’ by themselves cannot replace points 3 and 4

5 / 6

ModestIntermediate Level (Modest to adequate): 3 or 4 marks The information conveyed by the answer may be less well organised and not fully coherent. There is less use of specialist vocabulary, or specialist vocabulary may be used incorrectly. The form and style of writing is less appropriate.

Mentions any 3 of the 7 points.

4 marks: (1) OR (2) AND three others.3 / 4

LimitedLow Level (Poor to limited): 1 or 2 marksThe information conveyed by the answer is poorly organised and may not be relevant or coherent. There is little correct use of specialist vocabulary. The form and style of writing may be only partly appropriate.

One relevant point

OR a relevant, labelled diagram

2 marks: two points OR one point and a relevant labelled diagram1 / 2

[6]

M25.(a) vol = π0.0113 = (5.5753) 5.6 × 10−6 ( m3 ) (m = ρV )(= 8100 × 5.575 × 10−6 =) 0.045 (kg) ecf from first part

Allow use of g = 100.36 kg , 3.5 N from use of diameter rather than radius (max 3 from 4)

candidate's mass x g (W = 0.045160 × 9.81 = 0.44302 = 0.44 N)

any 2sf 4

(b) (i) The candidate’s writing should be legible and the spelling, punctuation and grammar should be sufficiently accurate for the meaning to be clear.The candidate’s answer will be assessed holistically. The answer will be assigned to one of three levels according to the following criteria.


Mentions all of the following:

• velocity (or speed) increases and then becomes constant (terminal velocity)• acceleration reduces to zero• forces become equal / balanced• weight (allow ‘gravity’) and drag / friction correctly identified

For 6 marks: In addition to the above, two of the following:• drag force increases with speed• (weight /downward force initially) greater than drag / friction etc• resultant force causes acceleration• Resultant force = W – drag• acceleration = gradient• acceleration is maximum (9.81) at the beginning

5-6

Intermediate Level (Modest to adequate): 3 or 4 marksThe information conveyed by the answer may be less well organised and not fully coherent. There is less use of specialist vocabulary, or specialist vocabulary may be used incorrectly. The form and style of writing is less appropriate.

Mentions the two following points:

• velocity (or speed) increases OR velocity (or speed) becomes constant / terminal velocity reached

• acceleration decreases OR acceleration becomes zero

ANDfor 3 marks: mentions one more valid point from the 4 above or from the 7 below:for 4 marks: at least two additional points with at least one from the ‘Forces’ list• acceleration = gradient• acceleration is maximum (9.81) at the beginning

Forces• weight greater than drag (before terminal velocity)• there is a resultant force downwards (before terminal velocity)• forces become equal / balanced / drag = weight• drag force increases with speed.• Resultant force = W – drag

Poor QWC may result in award of the lower mark within a band.3-4


Max 3 for mention of deceleration or increasing acceleration

One valid point from list belowFor two marks: Two valid pointsThe explanation expected in a competent answer should include a coherent selection of the following points concerning the physical principles involved and their consequences in this case.Mention of the points below may influence the mark given within each category:

• velocity increases• velocity becomes constant (terminal velocity)• acceleration is maximum (9.81) at the beginning• acceleration decreases (to zero)• weight greater than drag (before terminal velocity)• there is a resultant force downwards (before terminal velocity)• forces become equal / balanced / drag = weight• drag force increases with speed.• resultant force = W – drag• acceleration = gradient

valid point explaining why rapid decrease in velocity occurs when ball hits bottom of container. E.g. resultant upward force (decelerates the ball)

Several serious misconceptions may reduce a 2 mark answer to 11-2

(ii)

straight line with positive gradient from origin to first dotted line 3rd mark: Allow lines that become straight with a constant negative gradient after a curve.Vertical line at the end is not necessary.End of line must be between start of ‘e’ in ‘time’ and end of ‘w’ in ‘when’.

descending line (curved or straight but non-vertical) starting from a point on first dotted line (must not have negative velocity at any point) and the line may then become horizontal

curved line descending from first dotted line which is a continuation of the initial line (the gradient must be decreasing initially (a curve) and the line may then become horizontalAND extending up to second dotted line (with positive non-zero velocity)AND no incorrect continuation of line beyond second time line

Allow correct lines beyond the second time line: continuous zero velocity or falling below x axis and rising back to x axis (bouncing) but not reaching a higher speed than descent

ORstraight line with positive gradient from origin to first dotted line straight line with positive gradient from origin to first dotted lineAND ascending curved line with positive gradient decreasing, starting from a point on first dotted line (continuation of first line)

extending up to second dotted lineAND no incorrect continuation of line beyond second time line

3[13]

E1. Answers to this short question showed that most candidates had no real idea of how a fluorescent light tube worked and many accounts were pure guesswork. Some of the most common errors were, stating, in part (a), that the tube was under low pressure so that it would not break and in part (b), believing that the electrons were directed at the coating in order to make it glow.

E2. Too much time was spent by candidates repeating the wording of the question and explaining the wave particle duality. There was also a tendency to concentrate on one or two pieces of evidence, thereby excluding themselves from gaining full marks because of the lack of coverage. It was this aspect of the submitted answers that really governed the marks awarded, rather than candidates making errors. It was also clear that many candidates thought it only necessary to discuss the wave view of an electron and the particle view of an electromagnetic wave.

E3. Part (a) was answered well. Some candidates worked backwards from the frequency value and failed to score full marks, not because of the order of the calculations but because they did not include the stage of changing eV into Joules. It was also quite common to omit units for the wavelength. There were very few correct answers to part (b) (i). Answers to part (b) (ii) were better, but a number of good candidates misread the question and tried to determine the wavelength.

Only the more able candidates scored well in part (c), even though there were six marking points for the three available marks. All the misconceptions, e.g. the electrons hitting the coating, could be listed, but in truth most candidates did not know what happened in a fluorescent tube and wrote about anything that came to mind. A general feature of many answers was that candidates too readily combined more than one idea in a single sentence, thereby making their ideas unclear. It would be of benefit to most candidates to give simple clear statements, one sentence to each idea or process, and for these to run in a chronological order.

E5. Part (a) was not answered well and there was much confusion as to the processes involved in the photoelectric effect. However, a significant number of candidates confused the effect with excitation and line spectra. Only a minority of candidates were able to explain why the kinetic energy of the emitted electrons varied. A common response referred to the photons having a variety of energies even though the question stated that the light had a certain frequency. Most answers lacked significant detail such as the idea that a photon interacts with one electron and how threshold frequency and work function are related.

This question assessed quality of written communication and it was clear that most candidates appreciated that their answers needed a logical structure. However, few candidates were able to give a coherent and comprehensive answer.

Part (b) generated better answers although a significant minority of candidates did not appreciate the fact that the gradient of the maximum kinetic energy against frequency graph is the Planck constant.

Part (c) proved more difficult than expected and a number of candidates calculated the energy of the photon using the threshold frequency and failed to calculate the work function.

E6. The circuit diagrams drawn by candidates in part (a) (i) were generally not done well. Many did not include a means of varying the potential difference across the diode and the inclusion of a load resistor was rare. Less able candidates also confused the positioning of the voltmeter. There were very few occasions where a potential divider was used even though this is best practice for obtaining the full characteristics for the diode.

The descriptions of experimental procedure required for part (a) (ii) were generally thorough but some did suffer from a poor structure and this had an impact on the assessment of the Quality of Written Communication. Many candidates did not mention anything about reverse characteristics and it was noticeable that a significant minority did not appreciate that it was important to obtain readings with a potential difference of less than 1.0 V.

The calculation in part (b) (i) was done well and full marks were the norm. Part (b) (ii) proved to be not so straightforward and it was common to see candidates divide the potential difference across the diode by the resistance of the resistor. This proved to be one of the most discriminating questions on the paper.

E7. Candidates usually find questions involving a description of the formation of line spectra difficult. This proved to be the case this time and many candidates were very confused in their answers to part (a). A common error was to mix up this effect with the photoelectric effect even though the question mentioned the emission of photons. Many less able candidates talked about photons being absorbed rather than electron collisions and the idea of discrete energy levels and their relationship to the frequency of characteristic photons did not seem well understood. This question assessed the Quality of Written Communication and candidates tended to fail to gain marks because there was not a logical structure in the physics used in their explanations.

Part (b) (i) was not done well and many candidates confused the incident electrons with the orbital electrons and made statements such as ‘one of the electrons is excited and loses energy while the other one is in its ground state’. Candidates in the main, did not link this with part (a).

Part (b) (i) and (ii) proved to be much more accessible and full marks were common. The only common error was to use 9.0 eV instead of 8.0 eV as the energy of the photon.

E8.Part (a) proved straightforward and many candidates were able to calculate the resistance of the putty correctly. A minority of candidates did confuse resistance with resistivity and did not rearrange the equation from the data sheet. This question assessed significant figures and it was clear that there are still many candidates who do not appreciate that their final answer should reflect the precision of the data and in this case they should give their answer to two significant figures.

Part (b) assessed quality of written communication and this question proved quite challenging for the majority of candidates. It was extremely rare for candidates to obtain full marks and most answers were either modest and/or limited. The circuit diagrams seen were often penalised for careless errors such as incorrect symbols or the wrong positioning of meters.

It was rare for candidates to include a means of obtaining more than one result such as varying the length of the putty or using a variable resistor. Descriptions were often vague and hard to follow. Many candidates did not address the issue of precision in a convincing way and failed to describe how they would make all the measurements needed. It is clear from this paper and from previous papers that candidates find describing experiments difficult and would benefit from some practice of this skill.

E9. A significant proportion of candidates found part (a) difficult. It seems that many candidates were not familiar with an appropriate experiment that enables the variation of a thermistors resistance with temperature to be investigated. While many drew a correct circuit diagram, few were able to explain suitable techniques for varying the temperature of the thermistor. It was common to see answers that confused this experiment with one that investigated the I – Vcharacteristics of a filament lamp. This led candidates to suggest that it was appropriate to investigate resistance change by using increasing current to change the thermistor resistance. There was also much confusion as to how resistance was to be determined and the use of a graph of current against voltage was a regular response. Candidates incorrectly stated that they would determine the resistance of the thermistor by measuring the gradient of the graph. This would not be an appropriate method as the graph would be a curve and the gradient of the curve is not the resistance. It was extremely rare for water baths to be used for heating the thermistor and also many did not explain how they would measure the temperature of the thermistor. Many candidates did not address the issue of precision in a convincing way and failed to describe how they would make all the measurements needed. It is clear from this paper and from previous papers that candidates find describing experiments difficult and would benefit from some practice of this skill.

In contrast parts (b) and (c) were generally answered well and full marks were frequently seen. Less able candidates found it difficult to explain clearly the effect on the voltmeter reading if the battery did have an appreciable internal resistance. There is some evidence that candidates did not understand the meaning of the term negligible.

E10. Descriptive questions on quantum phenomena have caused candidates major problems in previous papers. Therefore, it was good to see so many confident answers to this question. Candidates seemed much more confident explaining excitation and line spectra than they are describing aspects of the photoelectric effect. Far less confusion was evident and a number of answers were awarded marks in the top band – a significant increase on previous questions that assessed the quality of written communication. Some less able candidates incorrectly tried to include a discussion of threshold frequency but this was comparatively rare. The correct use of technical terms such as ionisation and excitation were seen frequently and there was strong evidence that this aspect of quantum phenomena is more widely understood that is the case in other related areas of the specification.

Part (b) was generally answered well, although a minority of candidates incorrectly related the ionisation energy of hydrogen to a mole of hydrogen atoms. The conversion of electron volts to joules caused few problems and the majority of candidates appreciated that their answer should be quoted to three significant figures.

E11. Part (a) (i) required students to draw a suitable arrangement for investigating the variation in resistance of a piece of wire with temperature. Many students drew an appropriate circuit and misplaced voltmeters were far less in evidence in circuit diagrams. However, the majority did not show how the temperature of the wire was to be varied, in spite of being given the hint that the temperature range should be varied between 0°C and 100°C.

The description of the experiment required in part (a) (ii) was answered better than has previously been the case. Nevertheless, a significant proportion of students did not provide suitable methods for temperature variation. Suggestions such as ‘vary the temperature using a thermistor’ or ‘direct use of a Bunsen burner’ were not uncommon. It was clear that some students did not appreciate that the wire could be safely placed in a water bath.

Part (b) on critical temperature was answered well.

E12. Part (a) required students to describe the use of an oscilloscope to measure peak voltage and frequency of an alternating current supply. This was answered well by a good proportion of students and many were confident in their description of the use of the time base to determine frequency and the y-gain to measure peak voltage. In a number of good quality answers students mentioned switching off the time base and measuring peak to peak voltage so as to find an accurate rms voltage. It was evident however, that a minority of students were unfamiliar with the use of an oscilloscope and consequently gave very vague answers which scored few marks.The calculation of rms and peak current were well done with the only common error occurring when students assumed that the 12 V quoted in the question referred to peak voltage. Those doing this were not heavily penalised as their answers were carried forward in the subsequent calculations.

E13.In this question candidates needed to understand what is meant by an ohmic conductor and to describe an experiment to determine whether a particular component exhibited the necessary properties to be classed as this type of conductor. A significant proportion of candidates could not state what is meant by an ohmic conductor and responses such as “obeys Ohm‘s Law” and “something with resistance” were quite common.

A high proportion of correct circuit diagrams were seen in part (b)(i) and incorrectly placed voltmeters were rare. The main omission was a means of varying the current in the circuit. The experimental design caused problems and less than 15% of candidates wrote answers that qualified them for the top band. Some described the wrong experiment such as investigating the effect of temperature on the resistance of a thermistor. Those that did describe a correct experiment tended not to fully develop their answer. It was expected that a top band answer would have details of how a graph of results might be interpreted and in many cases this was only done in a very superficial manner. Candidates who did refer to a straight line indicating direct proportion often failed to mention that for this to be true the line must go through the origin. There was also a tendency for them to state that the gradient of the graph is equal to the

resistance. While this is true for a straight line graph going through the origin, it is not generally true and it was clear from a significant proportion of responses that candidates are not aware of this. It was good to see evidence of candidates planning their answers and given that they find these types of questions a challenge, this is a practice to be encouraged.

The remaining part of the question required knowledge of superconductors and although a high proportion of candidates failed to give a convincing use of superconductors the important property of a superconductor and the significance of critical temperature proved to be well understood.

E14.This question on particle classification generated some very impressive responses. Many candidates proved to be quite confident in their extended writing and top band answers were seen more frequently than has been the case in the past, particularly when questions refer to the photoelectric effect or line spectra

The main confusion that weaker candidates seem to have was an appreciation of which groups are affected by the strong nuclear force – a significant proportion seemed to think that this was only baryons

The most common omission in good answers was the identification of a similarity between hadrons and leptons. Overall however, the question worked well and candidates clearly enjoy this aspect of the specification and evidence for this is found in the confidence shown in many of the answers.

E16. Half of the candidates gained both marks for part (a). Nearly all pointed out that force is proportional to extension but half did not mention the ‘limit of proportionality’. Candidates need to ‘look for a second mark’.

Candidates had to apply their knowledge of Hooke’s law in part (b) (i). A significant number of candidates did not have a workable method and scored zero on this question. Many candidates picked up two marks by describing a simple comparison between extensions due to standard masses and the rock sample. A correct graphical approach and a point about accuracy were required for full marks. This question could perhaps form the basis of a practical activity to illustrate the significance of Hooke’s law in measuring mass or weight. A large number of candidates believed that the Young modulus of the spring should be found.

In part (b) (ii) most candidates knew how to stop the apparatus toppling over but a significant number could not describe this well enough to get the first mark, i.e. ‘put a weight on the stand’ did not gain marks but ‘put a weight on the base of the stand’ did. For the second mark, it was expected that candidates would give a correct explanation in terms of moments but hardly any candidates spotted this.

E17. Most scored very well on parts (a) (i) and (ii), which were fairly straightforward questions, though occasionally the answers to (a) (i) and (a) (ii) were given the wrong way round.

In part (b) Quality of Written Communication was assessment. Many candidates did not specify a distance measuring instrument (a ruler); perhaps failing to state the obvious.

Very few recognised the need to specify a suitable number of different loads over the complete range. This would be important in order to obtain the true shape of the curve; six marks were

only awarded if the candidate specified seven or more loads.

Many candidates forgot to include the unloading of the rubber cord in their answers and would have benefited greatly from re-reading the question and their answer here.

Candidates in a few centres appeared to use mnemonics to remember the elements necessary in answering this type of question; this seemed to work quite well.

E18. Part (a) (i) was answered well. Candidates immediately recognised a ‘suvat’ question and performed the calculation with no difficulty.

It was a similar story in part (a) (ii) with most candidates having no trouble in gaining both marks.

The responses to part (b) were, in general, a little disappointing. Responses that simply indicated that the ball decelerated and that balanced forces caused terminal velocity could achieve a maximum of four marks. For the higher marks (five or six), candidates needed to explain that the deceleration was decreasing and the drag force decreased as the ball slowed down. These more sophisticated answers discussing the forces acting were rare.

Some candidates compared different quantities, eg ‘acceleration balanced out the weight’. Some clearly thought that the graph showed acceleration not velocity.

Unfortunately, almost every candidate felt the need to describe the motion of the ball before it entered the liquid before embarking on answering the question. In many cases half or more of the answer space was used up before any marks were scored. Perhaps many candidates felt this was a suitable introduction to their answer. However, as a general rule, marks will not be awarded for correct physics statements that do not address the question. Inclusion of irrelevant detail in this case resulted in an excessive number of candidates requiring additional sheets to complete their answers.

E19. Part (a) assessed the candidates’ quality of written communication. Most responses were lacking in detail and there was a general lack of awareness of what is required in a question such as this. The question asked how the data to determine the Young modulus could be obtained accurately. A good response would mention the quantities needed and the measuring instruments required with an indication of how the apparatus is arranged.

Many candidates did not list all the measurements (original length, extended length, diameter) or the quantities derived from these (extension and cross sectional area) that would be needed for the calculation of Young modulus. Failure to state that diameter or cross-sectional area would be measured limited the candidate to two marks out of six.

Candidates were also expected to make a comment about accuracy and to get beyond two marks they needed to mention some form of repeat or the use of a range of masses or the use of a wire of 1.0 m or more.

The specification states that candidates should know a simple method for the determination of

the Young modulus. This implies that they do not need to be familiar with Searle’s apparatus. Some candidates scored well when giving a detailed account of Searle’s. However, those who seen Seale’s apparatus but only partially understood how to use it, tended to fare less well than those who described stretching a wire along a bench. It should be noted that the phrase ‘simple method’ does not imply that a non-graphical method will suffice. Many candidates described substituting one-off measurements into the Young modulus equation. An accurate method, at least in a school laboratory, should involve using a range of loads and extensions. We would recommend that centres who have Searle’s apparatus do demonstrate it and give students the opportunity to use it. However, the simpler method of stretching horizontally on a bench can be presented as the preferred option for a descriptive question such as this for all but the most able and meticulous students.

Diagrams produced by candidates here tended to lack detail and labelling and many did not go on to state that the load or force had to be found from the mass.

In part (b) (i), the line of best fit was drawn well by 55%. Some drew a straight line but did not produce a curved section at the top. Some did not draw the line going through the origin. However, it was felt that in this case candidates should expect a stress-strain graph to go through the origin and should have extended to the origin. Best fit lines are taught extensively at KS3 and KS4. However, the evidence suggests that candidates continue to lose marks on these at AS level so a lot of practice is needed.

For part (b) (ii) most candidates did very well and picked up three or four marks. A significant percentage of candidates who had drawn an incorrect best fit line did pick up full marks for the gradient calculation. Of those who did not, many chose the wrong unit eg Nm–1, Nm or ‘pa’ rather than Pa. Some candidates could have been awarded a method mark if they had drawn a triangle as evidence that they where calculating the gradient. Many candidates could have set out their answer in a much clearer manner.

E20. For part (a), most candidates found the increase in gravitational potential energy without any problems.

In part (b) (i), half of all candidates realised that the gain in kinetic energy could be calculated from the loss in gravitational potential energy. Many candidates wrote down the equation for kinetic energy and were unable to make progress from there.

A large majority of candidates were able to rearrange the kinetic energy equation in part (b) (ii) and calculated successfully the speed from their answer to part (b) (i).

The direction of the arrow did not cause any problems in part (c). However, the placement of arrow did. The tail of the arrow should originate close to soles of gymnast’s feet but the majority placed it to the side, above or below this position.

Part (d) was quite a tricky question, but it was answered well by a large number of candidates using a = Δv/t with their value of speed from part (b) (ii).

In part (e), a large number gained four marks or more on part (e) and the Quality of Written Communication was generally very good. The most common reason for not reaching the higher marks was focusing only on transformations and not mentioning the work done by or on the gymnast in order to reach a greater height.

E21. Some candidates forgot to answer the second part of the question and did not make adequate reference to the features of the stationary wave shown. The first part (how a stationary wave is formed) was answered well. Many candidates used the term ‘superimpose’ instead of ‘superpose’ and typically a candidate would lose a mark for this.

E22. Part (a), an extended answer question, yielded the highest marks of any so far on this examination. It was a standard situation and candidates were very familiar with the physics so, the majority gained more than half marks. It was not too difficult to get five marks out of six however; full marks were only given to the most complete of responses.

It was pleasing that only a few misinterpreted the question and chose the wrong path; inappropriate discussion of ‘gratings’ was only seen a few times. The majority of candidates still recommend protecting the eyes from laser radiation by wearing ‘goggles’. If the candidate insists on giving this advice, they must specify ‘goggles designed to protect the eyes from laser radiation’ or words to that effect, since ordinary lab goggles would provide no protection.

Marks were still sometimes lost due to candidates not specifying measuring instruments. However, there was a marked improvement on previous experimental description questions. Even the humble ‘ruler’ should be specified if it is to be used.

Part (b) was a common question and perhaps, therefore, it should have yielded a higher percentage of full-marks answers. The most common error was to say that the two sources are ‘in phase’. However, it should be stressed that coherent sources have a fixed phase relationship, so they are not necessarily in phase.

Many candidates did not include the single slit and many did not label the slits in answer to part (c).

A significant number did not attempt the question at all. Surprisingly, less than half scored any marks at all on this question.

In part (d), some candidates thought that the fringes for white light would be further apart. This would only be true if the laser were red; the candidate would have to state this assumption to gain the mark.

Some lost marks because they did not make it clear which light source they were referring to.

Most candidates gained the mark in part (e) for mentioning destructive interference but did not go on to explain that the cancellation is caused by the waves meeting in antiphase or with half a wavelength path difference.

E23. Part (a) was done well by most students. However, many would have benefitted from using a protractor to get the angles between the zero order and the two first-order beams roughly equal.

In part (b), the basic requirement is that students know that dark lines (absorption lines) are seen on the spectra from stars and that these reveal elements present in the outer layers of the star. The mark scheme also credited other uses of a stars spectrum. Many students had the idea that spectral lines revealed elements but few knew about absorption lines. This is an area where students who have taken PHYA1 first may have an advantage since they have studied atomic energy levels and may have seen absorption spectra.

Labelling a laser, diffraction grating and some sort of screen or suitable detector was all that was required for the two marks in part (c) (i). Many students missed out the screen. Some had double slits instead of a grating.

Part (c) (ii) was, in general, poorly answered. Many students did not seem to be familiar with this practical and instead described a two-slit approach to measuring wavelength. Those who seemed familiar with the procedure tended not to fully answer the question which asked for details of all the measurements and necessary calculations. The candidate who leaves out these details is unlikely to be able to score more than two marks out of six even if they have given a reasonable general description of the experiment. For example, they must include details of how the angle is to be measured eg by measuring the distance between the zero order and the first-order beam (using a ruler) and the distance between the screen and the grating. They must then use tan θ = O/A to calculate the angle. Where students knew which equation to use, they tended to know insufficient detail to score more than a few marks. Of those students who did describe the use of a grating, many did not know the meanings of the symbols in the equation eg, d was often thought to be the distance between grating and screen and n, the number of lines per mm or even the refractive index of air. Many described measuring the grating spacing with micrometers or metre rules, forgetting that the question stated that the lines per mm are known.

In short, many of the students who took this exam seemed poorly prepared for this type of question. They were, in some cases, able to produce an answer from a past paper for a closely related, but significantly different, question. Many seemed unaware of the style and quality of answer expected.

Most answers were vague, the literacy level was generally poor and there was a lack of detail regarding the measurements and what should be done with them. This is often the case in the January examination, but it is possible to improve the necessary skills even in the short preparation time available. A few structured lessons on answering this type of question can to be incorporated into schemes of work, allowing students to be fully aware of the expectations.

E24.This was a very accessible question given that there are several past paper questions that address the same issue of the formation of stationary waves.

Candidates did very well on this question but there was a lack of understanding of some wave terminology evident. Candidates often correctly explained that two progressive waves travelling in opposite directions give rise to a stationary wave. However, they often described the waves as having a constant phase difference and being coherent. Many also thought that a node is formed by a peak cancelling a trough and an antinode is formed by a peak meeting peak or a trough

meeting a trough.

An antinode is formed at a position where the displacements of the two waves are always in the same direction and of equal magnitude, they are not always peaks or troughs. A node is formed where the waves always cancel and this is not only due to a peak meeting a trough but is due to the waves having equal and opposite displacements at the position of the node. Another common misconception was that two troughs meet to give destructive interference.

The two progressive waves have a constantly varying phase difference. It would be correct to say that at the position of a node, the two waves are always in antiphase and they arrive at antinode in phase.

E25.(a) Many students seemed unaware that the volume of a sphere was given on the data sheet. Because of this they guessed at the formula often electing to use π2.

Many of those who did find the correct formula still did not manage to calculate the correct volume due to numerical errors.

There was also the usual issue with candidates believing mass and weight are the same thing and giving the weight in kg. Many did not round their answer to the correct number of significant figures which should have been 2.

(b) Some very good, detailed and correct answers here. However, a common error was to confuse decreasing acceleration with deceleration.

(i) Many candidates started well and then at the end started padding out their answer, often with incorrect and contradictory statements, e.g.: ‘so therefore the longer the time, the slower the velocity and the acceleration.’

Again, candidates were sometimes not accurate and careful in describing motion and gave answers similar to the following:‘As the gradient of the graph decreases this is showing a decrease in velocity and acceleration’.‘After half of the time has passed, the ball stops and travels at a constant speed’.‘As the speed of the ball increases, the resistive force increases, resulting in the ball slowing down’.

The was also the usual problem with comparison of different quantities, a typical example being:

‘At first the drag acting on the ball is greater than the acceleration, so the velocity increases until its equal to the drag force.’

(ii) The examiners bold looking for a straight line to begin with. However, many candidates produced a curve showing significant air resistance.

It is possible that the ball bearing could hit the water at a speed less than its terminal velocity in oil. Therefore candiates who correctly described this were able to get full credit – though perhaps this answer was not the most sensible approach.

There were many wrong answers showing the ball bearing‘s acceleration decreasing in air or increasing in the water.

The challenge is to get students to accurately show how a given quantity changes with time for a body in motion. A teacher could choose a range of examples of objects whose velocity and acceleration change with time and ask students to sketch

and describe them. They could then display the results using a visualizer or a camera linked to a projector in order to facilitate discussion.

Documents

… · Web viewshows the velocity-time graph for steel ball A. Figure 2 Explain the shape of the graph in Figure 2. Your account should include • how the velocity and acceleration