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iGCSE Longer Answer Practice Exam Questions
Qu. Mark MaxImprovement
pointSKREAM
Overall Comment
Page 1 of 35
S I made a silly slip
K I just did not know the science
R I misread the question
E My writing was not clear/ detailed
A I did not apply the knowledge
M I applied the maths incorrectly
Questions…
Q1.The figure below shows a skateboarder jumping forwards off his skateboard.
The skateboard is stationary at the moment the skateboarder jumps.
(a) The skateboard moves backwards as the skateboarder jumps forwards.
Explain, using the idea of momentum, why the skateboard moves backwards.
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(b) The mass of the skateboard is 1.8 kg and the mass of the skateboarder is 42 kg.
Calculate the velocity at which the skateboard moves backwards if the skateboarder jumps forwards at a velocity of 0.3 m / s.
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Velocity of skateboard = ____________________ m / s(3)
(Total 6 marks)
Page 2 of 35
Q2.Electrical circuits have resistance.
(a) Draw a ring around the correct answer to complete the sentence.
When the resistance of a circuit increases, the current in the circuit
decreases.
increases.
stays the same.
(1)
(b) Use the correct answer from the box to complete each sentence.
a filament bulb an LED an LDR
An electrical component which has a resistance that increases as the
temperature increases is _________________________ .
An electrical component which emits light only when a current flows through it
in the forward direction is _________________________ .(2)
(c) When some metals are heated the resistance of the metal changes.
The equipment for investigating how the resistance of a metal changes when it is heated is shown in the diagram.
In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
Describe an investigation a student could do to find how the resistance of a metal sample varies with temperature. The student uses the equipment shown.
Include in your answer:
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• how the student should use the equipment
• the measurements the student should make
• how the student should use these measurements to determine the resistance
• how to make sure the results are valid.
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(d) The table shows some data for samples of four metals P, Q, R and S.
The metal samples all had the same cross-sectional area and were the same length.
Metal sample Resistance at 0°C in ohms
Resistance at 100°C in ohms
P 4.05 5.67
Q 2.65 3.48
R 6.0 9.17
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S 1.70 2.23
A graph of the results for one of the metal samples is shown.
Temperature in °C
(i) Which metal sample, P, Q, R or S, has the data shown in the graph? (1)
(ii) One of the results is anomalous. Circle this result on the graph.(1)
(iii) Suggest a reason for the anomalous result.
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(iv) The same equipment used in the investigation could be used as a thermometer known as a ‘resistance thermometer.’
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Suggest two disadvantages of using this equipment as a thermometer compared to a liquid-in-glass thermometer.
1. ____________________________________________________________
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2. ____________________________________________________________
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(Total 14 marks)
Q3.(a) Nuclear fuels and the wind are two of the energy sources used to generate
electricity in the UK.
Explain the advantages of using energy from nuclear fuels to generate electricity rather than using energy from the wind.
Include in your answer a brief description of the process used to generate electricity from nuclear fuels.
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(b) In the UK, most electricity is generated in power stations that emit carbon dioxide into the atmosphere. The impact of these power stations on the environment could be reduced by the increased use of 'carbon capture' technology.
Describe how 'carbon capture' would prevent the build-up of carbon dioxide in the atmosphere.
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(Total 6 marks)
Q4.In the early part of the 20th century, scientists used the ‘plum pudding’ model to explain the structure of the atom.
Following work by Rutherford and Marsden, a new model of the atom, called the ‘nuclear’ model, was suggested.
Describe the differences between the two models of the atom.
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Q5.According to kinetic theory, all matter is made up of small particles. The particles are constantly moving.
Diagram 1 shows how the particles may be arranged in a solid.
Diagram 1
(a) One kilogram of a gas has a much larger volume than one kilogram of a solid.
Use kinetic theory to explain why.
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(b) Diagram 2 shows the particles in a liquid. The liquid is evaporating.
Diagram 2
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(i) How can you tell from Diagram 2 that the liquid is evaporating?
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(ii) The temperature of the liquid in the container decreases as the liquid evaporates.
Use kinetic theory to explain why.
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(Total 8 marks)
Q6.Describe, in as much detail as you can, how the energy stored in coal is transferred into electrical energy in a power station.
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Q7.The map below shows the position of two towns, A and B, on the banks of a large river estuary.
A is an important fishing and ferry port.
The wind usually blows from the west. The major roads and railways are shown.
A power station is to be built in area X to generate electricity for the region.
The choice is between a nuclear power station and a coal fired power station.
(a) State the advantages and disadvantages of the two methods of generating electrical energy.
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(b) Which method would you choose for this site?
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Explain the reason for your choice.
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(Total 9 marks)
Q8.(a) Figure 1 shows the horizontal forces acting on a moving bicycle and cyclist.
Figure 1
(i) What causes force A?
Draw a ring around the correct answer.
friction gravity weight(1)
(ii) What causes force B?
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(iii) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
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Figure 2 shows how the velocity of the cyclist changes during the first part of a journey along a straight and level road. During this part of the journey the force applied by the cyclist to the bicycle pedals is constant.
Figure 2
Time
Describe how and explain, in terms of the forces A and B, why the velocity of the cyclist changes:
• between the points X and Y
• and between the points Y and Z, marked on the graph in Figure 2.
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(b) (i) The cyclist used the brakes to slow down and stop the bicycle.
A constant braking force of 140 N stopped the bicycle in a distance of 24 m.
Calculate the work done by the braking force to stop the bicycle. Give the unit.
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Work done = ______________________________(3)
(ii) Complete the following sentences.
When the brakes are used, the bicycle slows down. The kinetic energy of the
bicycle ______________________________ .
At the same time, the ______________________________ of the brakes
increases.(2)
(Total 13 marks)
Q9.Stars do not stay the same forever.
(a) Over billions of years the amount of hydrogen in a star decreases. Why?
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(b) Describe how a massive star (at least five times bigger than the Sun) will change at the end of the main stable period.
To gain full marks in this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words.
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(c) The inner planets of the solar system contain atoms of the heaviest elements.
(i) Where did these atoms come from?
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(ii) What does this tell us about the age of the solar system compared with many of the stars in the Universe?
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(Total 7 marks)
Q10.A student carries out an investigation using a metre rule as a pendulum.
(a) Diagram 1 shows a metre rule.
Diagram 1
(i) Draw, on Diagram 1, an X to show the position of the centre of mass of the rule.
(1)
(ii) State what is meant by the ‘centre of mass of an object’.
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(b) The student taped a 100 g mass to a metre rule.
She set up the apparatus as shown in Diagram 2.
She suspended the metre rule from a nail through a hole close to one end, so she could use the metre rule as a pendulum.
The distance d is the distance between the nail and the 100 g mass.
Diagram 2
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(i) Draw, on Diagram 2, a Y to show a possible position of the centre of mass of the pendulum.
(1)
(ii) The student carried out an investigation to find out how the time period of the pendulum varies with d.
Some of her results are shown in the table.
Time for 10 swings in seconds
d in cm Firsttest
Secondtest
Thirdtest
Meanvalue
Mean time for
1 swing inseconds
10.0 15.3 15.4 15.5 15.4 1.54
30.0 14.7 14.6 14.7 14.7 1.47
50.0 15.3 15.6 15.4 15.4 1.54
70.0 16.5 16.6 16.5
Complete the table.
You may use the space below to show your working.
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(iii) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
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Describe how the student would carry out the investigation to get the results in the table in part (ii).
You should include:
• any other apparatus required
• how she should use the apparatus
• how she could make it a fair test
• a risk assessment
• how she could make her results as accurate as possible.
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(c) A graph of the student’s results is shown below.
Distance d in cm
(i) Describe the pattern shown by the graph.
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(ii) The student thinks that the measurements of time for d = 10 cm might be anomalous, so she takes a fourth measurement.
Her four measurements are shown below.
15.3 s 15.4 s 15.5 s 15.3 s
State whether you consider any of these measurements to be anomalous.
Justify your answer.
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(Total 16 marks)
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Q11.(a) A resistor is a component that is used in an electric circuit.
(i) Describe how a student would use the circuit to take the readings necessary to determine the resistance of resistor R.
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(ii) Explain why the student should open the switch after each reading.
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(iii) In an experiment using this circuit, an ammeter reading was 0.75 A.The calculated value of the resistance of resistor R was 16 Ω.
What is the voltmeter reading?
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Voltmeter reading = ________________ V(2)
(iv) The student told his teacher that the resistance of resistor R was 16 Ω.
The teacher explained that the resistors used could only have one of the following values of resistance.
10 Ω 12 Ω 15 Ω 18 Ω 22 Ω
Suggest which of these resistors the student had used in his experiment.
Give a reason for your answer.
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(b) The diagram shows a fuse.
Describe the action of the fuse in a circuit.
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(Total 15 marks)
Page 20 of 35
Q12.In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
There are two types of traditional transformer; step-up and step-down.
Describe the similarities and differences between a step-up transformer and a step-down transformer.
You should include details of:
• construction, including materials used
• the effect the transformer has on the input potential difference (p.d.).
You should not draw a diagram.
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Q13.(a) Figure 1 shows one way that the motor effect can be demonstrated.
Figure 1
When the switch is closed the copper wire moves.
Describe how the direction that the copper wire will move can be predicted using Fleming's Left Hand rule.
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Figure 2 shows the apparatus a student used to measure the force acting on a conducting wire in a magnetic field.
The wire is clamped to stop it moving.
Figure 2
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This is the method used.
1. The student set the reading on the balance to zero.
2. The student closed the switch and recorded the new balance reading.
3. The student then repeated the procedure three more times. Each time the current was kept the same.
(b) The four balance readings taken by the student are given in the box.
0.21 0.23 0.25 0.23
Estimate the uncertainty in the balance readings taken by the student.
Show how you estimate the uncertainty.
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Uncertainty = ± ____________________ mg(2)
(c) The student changed the current in the wire and recorded the new balance reading.
The table shows all of the data recorded by the student.
Current in the wire 2.2 A
Page 23 of 35
Balance reading 0.40 g
Magnetic flux density 0.030 T
Gravitational field strength 9.8 N/kg
Calculate the length of the wire in the magnetic field.
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Length of wire = ____________________ m(5)
(Total 11 marks)
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Mark schemes
Q1.(a) momentum before (jumping) = momentum after (jumping)
accept momentum (of the skateboard and skateboarder) is conserved
1
before (jumping) momentum of skateboard and skateboarder is zeroaccept before (jumping) momentum of skateboard is zeroaccept before (jumping) total momentum is zero
1
after (jumping) skateboarder has momentum (forwards) so skateboard must have (equal) momentum (backwards)
answers only in terms of equal and opposite forces are insufficient1
(b) 7accept –7 for 3 marksallow 2 marks for momentum of skateboarder equals 12.6or0 = 42 × 0.3 + (1.8 × –v)orallow 1 mark for stating use of conservation of momentum
3[6]
Q2.(a) decreases
1
(b) a filament bulballow bulb
1
an LED1
(c) Marks awarded for this answer will be determined by the Quality of Communication (QoC) as well as the standard of the scientific response.
0 marksNo relevant content.
Level 1 (1−2 marks)There is a basic description of the method. This is incomplete and would not lead to any useful results.
Level 2 (3−4 marks)There is a description of the method which is almost complete with a few minor omissions and would lead to some results.
Level 3 (5−6 marks)
1
There is a detailed description of the method which would lead to valid results.To gain full marks an answer including graph, or another appropriate representation of results, must be given.
examples of the physics points made in the response:
• read V and I• read temperature• apply heat
allow hot water to cool• read V and I at least one other temperature• determine R from V / I• range of temperatures above 50 °C
extra detail:• use thermometer to read temperature at regular intervals of temperature• remove source of heat and stir before taking readings• details of attaining 0 °C or 100 °C• last reading taken while boiling• graph of R against T• at least 3 different temperatures
6
(d) (i) Q1
(ii) (80, 3.18)1
(iii) any one from:
• measurement of V too small• measurement of I too big• incorrect calculation of R• thermometer misread
allow misread meterignore any references to an error that is systematic
1
(iv) any two from:
• not portableallow requires a lot of equipment allow takes time to set up
• needs an electrical supply• cannot be read directly
accept it is more difficult to read compared to liquid-in-glass2
[14]
Q3.(a) answers must be in terms of nuclear fuels
concentrated source of energyidea of a small mass of fuel able to generate a lot of electricity
1
that is able to generate continuously
2
accept it is reliableor can control / increase / decrease electricity generationidea of available all of the time / not dependent on the weatherignore reference to pollutant gases
1
the energy from (nuclear) fission1
is used to heat water to steam to turn turbine linked to a generator1
(b) carbon dioxide is not released (into the atmosphere)1
but is (caught and) stored (in huge natural containers)1
[6]
Q4.any two pairs from:
to gain credit it must be clear which model is being describeddo not accept simple descriptions of the diagram without comparison
• nuclear model mass is concentrated at the centre / nucleus (1)accept the nuclear model has a nucleus / the plum pudding model does not have a nucleus for 1 mark
plum pudding model mass is evenly distributed (1)
• nuclear model positive charge occupies only a small part of the atom (1)
plum pudding model positive charge spread throughout the atom (1)
• nuclear model electrons orbit some distance from the centre (1)accept electrons in shells / orbits provided a valid comparison is made with the plum pudding model
plum pudding electrons embedded in the (mass) of positive (charge) (1)do not accept electrons at edge of plum pudding
• nuclear model the atom mainly empty space (1)
plum pudding model is a ‘solid’ mass (1)[4]
Q5.(a) there are strong forces (of attraction) between the particles in a solid
accept molecules / atoms for particles throughout accept bonds for forces
1
(holding) the particles close togetherparticles in a solid are less spread out is insufficient
3
1
or
(holding) the particles in a fixed pattern / positions
but in a gas the forces between the particles are negligibleaccept very small / zero for negligible accept bonds for forces
1
so the particles spread out (to fill their container)accept particles are not close together gas particles are not in a fixed position is insufficient
1
(b) (i) particles are (shown) leaving (the liquid / container)accept molecules / atoms for particles throughoutaccept particles are escapingparticles are getting further apart is insufficient
1
(ii) accept molecules / atoms for particles throughout accept speed / velocity for energy throughout
particles with most energy leave the (surface of the) liquidaccept fastest particles leave the liquid
1
so the mean / average energy of the remaining particles goes down1
and the lower the average energy (of the particles) the lower the temperature (of the liquid)
1[8]
Q6.coal has chemical energy when burnt heat/energy produced longestused to boil water/make steam sequenceused to turn turbine(s)which now have keturbine(s) turn generator(s)(where (ke) transferred electrical energy)(or electrical energy produced )
any 5 for 1 mark each[5]
Q7.(a) must give one advantage and one disadvantage of each to get 4 marks
and 2 further scoring points
4
Advantages and disadvantages relevant to:(1) health risk(5) cost(6) environmental factors(7) transport/ storagee.g. common coal / nuclear – high cost of building both
anti-nuclear examplesnuclear fuel transported on roads/rail in regionpossible effects on public health in surrounding areahigh cost of de-commissioninglong life very active waste materials producedhow waste materials stored safely for a long time
anti-coal examplesunsightlypollutionsupplies of fuel limitedacid rainnon-renewable
pro-nuclear examplesfuel cheapno foreseeable fuel shortage
pro-coal examplessafereliablelarge coal reservesdisposal of solid waste is easier
to max 66
(b) choice 0 marks
any three valid reasons each with explanation, which may or may not be comparisons with other fuel
But
at least two of which must be relevant to this site3
[9]
Q8.(a) (i) friction
1
(ii) air resistanceaccept dragfriction is insufficient
1
(iii) Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. Examiners should also refer to the information on page 5, and apply a ‘best-fit’ approach to the marking.
5
0 marksNo relevant content.
Level 1 (1–2 marks)There is an attempt to explain in terms of forces A and B why the velocity of the cyclist changes between any two pointsora description of how the velocity changes between any two points.
Level 2 (3–4 marks)There is an explanation in terms of forces A and B of how the velocity changes between X and Y and between Y and Zora complete description of how the velocity changes from X to Z.oran explanation and description of velocity change for either X to Y or Y to Z
Level 3 (5–6 marks)There is a clear explanation in terms of forces A and B of how the velocity changes between X and Zanda description of the change in velocity between X and Z.
examples of the points made in the responseextra information
X to Y • at X force A is greater than force B • cyclist accelerates • and velocity increases • as cyclist moves toward Y, force B (air resistance)
increases (with increasing velocity) • resultant force decreases • cyclist continues to accelerate but at a smaller value • so velocity continues to increase but at a lower rateY to Z • from Y to Z force B (air resistance) increases • acceleration decreases • force B becomes equal to force A • resultant force is now zero • acceleration becomes zero • velocity increases until… • cyclist travels at constant / terminal velocity
accept speed for velocity throughout6
(b) (i) 3360allow 1 mark for correct substitution,ie 140 × 24 provided no subsequent stepaccept 3400 for 2 marks if correct substitution is shown
2
joule / Jdo not accept jdo not accept Nm
1
(ii) decreases
6
accept an alternative word / description for decreasedo not accept slows down
1
temperatureaccept thermal energyaccept heat
1[13]
Q9.(a) converted into helium
accept helium createdaccept converted into heavier elementsaccept used up in nuclear fusion / to produce energydo not accept any reference to burning
1
(b) turns / expands into a red giantcontradictions negate mark
1
contracts and explodes or becomes a supernova1
may form a (dense) neutron star or (if enough mass shrinks to) form a black holeaccept forms a neutron star and (then) a black hole
1
Quality of written communicationcorrect points must be in sequence
1
(c) (i) supernova or remains of an earlier starignore super nebula
1
(ii) younger or not formed at the time of the Big Bang1
[7]
Q10.(a) (i) X placed at 50 cm mark
1
(ii) point at which mass of object may be (thought to be) concentrated1
(b) (i) Y placed between the centre of the rule and the upper part of mass1
(ii) 16.5allow for 1 mark(16.5 + 16.6 +16.5) / 3
2
7
1.65value consistent with mean value givenonly penalise significant figures once
1
(iii) Marks awarded for this answer will be determined by the quality of communication as well as the standard of the scientific response. Examiners should apply a ‘best-fitߣ approach to the marking.
0 marksNo relevant content
Level 1 (1 – 2 marks)A description of a method which would provide results which may not be valid
Level 2 (3 – 4 marks)A clear description of a method enabling some valid results to be obtained. A safety factor is mentioned
Level 3 (5 – 6 marks)A clear and detailed description of experiment. A safety factor is mentioned. Uncertainty is mentioned
examples of the physics points made in the response:
additional apparatus
• stopwatch
use of apparatus
• measure from hole to centre of the mass• pull rule to one side, release• time for 10 swings and repeat• divide mean by 10• change position of mass and repeat
fair test
• keep other factors constant• time to same point on swing
risk assessment
• injury from sharp nail• stand topple over• rule hit someone
accuracy
• take more than 4 values of d• estimate position of centre of slotted mass• small amplitudes• discard anomalous results• use of fiducial marker
6
(c) (i) initial reduction in T (reaching minimum value) as d increases1
8
after 30 cm T increases for higher value of d1
(ii) (no)
any two from:
• fourth reading is close to mean• range of data 0.2 s / very small• variation in data is expected
2[16]
Q11.(a) (i) any six from:
• switch on• read both ammeter and voltmeter
allow read the meters• adjust variable resistor to change the current• take further readings• draw graph• (of) V against I
allow take mean• R = V / I
allow take the gradient of the graph6
(ii) resistor would get hot if current left on1
so its resistance would increase1
(iii) 12 (V)0.75 × 16 gains 1 mark
2
(iv) 15 (Ω)1
16 is nearer to that value than any other1
(b) if current is above 5 A / value of fuse1
fuse meltsallow blows / breaksdo not accept exploded
1
breaks circuit1
[15]
Q12.9
Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. Examiners should also apply a ‘best-fit’ approach to the marking.
0 marksNo relevant / correct content.
Level 1 (1–2 marks)Either there is an attempt at a description of the construction of a transformer
or
a correct statement of the effect of one type of transformer on the input p.d.
Level 2 (3–4 marks)There is a description of the construction of a transformeranda correct statement of the effect of one type of transformer on the input p.d.
Level 3 (5–6 marks)There is a clear description of the construction of a transformerandthere is a correct description of how transformers affect the input p.d.
details of construction:extra information
a (laminated) core
core is made from a magnetic material / iron
2 coils
the coils are made from an electrical conductor / copper
the coils are covered in plastic / insulation
the coils are (usually) on opposite sides
step-up transformer has more turns on secondary coil than (its) primary (or vice versa)
step-down transformer has fewer turns on secondary coil than (its) primary (or vice versa)
effect on input p.d. :
step-up transformer, the output p.d. is greater (than the input p.d.)accept voltage for p.d.
step-down transformer, the output p.d. is lower (than the input p.d.)6
[6]
Q13.(a) point the first two fingers and thumb of the left hand so they are at
right angles1
point the first / index finger in the direction of the magnetic field 10
from North to South1
point the second / middle finger in the direction of current from positive to negative
allow in the direction of conventional current for positive to negative
1
the thumb then points in the direction of the force in this case to the left
1
(b) mean of 0.23 calculated1
0.021
(c) F = 0.40 × 10–3 × 9.81
F = 3.92 × 10–3 (N)1
3.92 × 10–3 = 0.03 × 2.2 × Lup to 3 marks to be awarded for a correct calculation of L using an incorrect value of F
1
1
L = 0.059 (m)an answer of 0.059 (m) scores 5 marks
1[10]
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