Edexcel GCE Physics 2008 Unit 4 Topic 3 Particle Physics Test With Marks Scheme 15_16

8/20/2019 Edexcel GCE Physics 2008 Unit 4 Topic 3 Particle Physics Test With Marks Scheme 15_16

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Physics Advanced

Test 4 Particle Physics

Date: 18 January 2016

Time: 1 hour 30 minutes

RAW MARK PERCENTAGE LETTER GRADE


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11

Answer ALL questions.

For questions 1 – 10 select one answer from A to D and put a cross in the box ( ) If you

change your mind, put a line through the box ( ) and then mark your new answer with a

cross

1. The number of neutrons in a nucleus of 23 is

(Total 1 mark)

2. Which of the following is not a valid conclusion from Rutherford’s alpha scattering

experiment?

(Total 1 mark)

3. The K+ is likely to decay to

(Total 1 mark)

1

A 11

B 23

C 12

D 34

A Electrons orbit the nucleus in specific distances

B The nucleus is charged

C The nucleus contains most of the mass of the atom

D The nucleus must be very small compared to the atom

3. The K+ is likely to decay to

A

B

C

D

(Total 1 mark)


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4. The Large Hadron Collider is designed to accelerate protons to very high energies for particle

physics experiments.

Very high energies are required to

A annihilate hadrons

B collide hadrons

C create particles with large mass

D produce individual quarks

(Total 1 mark)

5.

A proton enters a particle accelerator. As it emerges from the accelerator its mass is measuredto be 3.8 × 10

– 29kg.

It can be concluded that the proton

(Total 1 mark)

6. A student suggests that two colliding protons could undergo the interaction

p + p p + n + π-

Which of the following statements is true?

A The interaction is not possible because charge is not conserved.

B The interaction is not possible because the number of particles is not conserved.

C The colliding protons must move in opposite directions.

D The resulting particles must have a very high value of kinetic energy.

(Total 1 mark)

2

A has become a positron

B is travelling in a circle

C is travelling at non-relativistic speed

D is travelling at close to the speed of light


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7. The path followed by an electron of momentum p, carrying charge – e, which enters a

magnetic field at right angles, is a circular arc of radius r.

What would be the radius of the circular arc followed by an α particle of momentum 3p, which

entered the same field at right angles?

(Total 1 mark)

8. The mass in MeV/c2 of a 1.8 × 10-29

kg positron is

A

(Total 1 mark)

9. In a linac, the particles gain kinetic energy because:

A the tubes increase in length

B mass is converted to energy due to ΔE=Δmc2

C a potential difference is applied across tubes

D a magnetic field is presented within each tube

(Total 1 mark)

3

A r

B 1.5 r

C 3 r

D 6 r

A 10

B 3.2 × 10-59

C 3.3 × 10-8

D 1.0 × 107

(Total 1 mark)


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10. The diagram shows the path of an electron in a bubble chamber.

ε

0 t

ε

ε

0 t 0 t

A B

ε

ε

0 t 0 t

C D

(Total 1 mark)

4

10. Data at the back of the examination paper can be used with the formula ΔE = c2 Δm tocalculate

A the amount of energy in a proton.

B the mass of coal that produces 6 MJ of energy when burnt.

C the energy produced when an electron and a positron annihilate.

D the energy produced when two protons collide.

(Total 1 mark)


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11. The figure shows the path of an electron and a positron in a uniform magnetic field.

(a) State the feature of the paths that shows that the electron has different sign of charge from a

positron. (1)

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(b) State the feature of the paths that shows that the electron and the positron have the same

magnitudes of momentum. (1)

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(c) Calculate the force on the positron as it moves through the uniform magnetic field with a

speed of 1.7 x 107

m/s. (2)

Magnetic field strength = 0.45 T

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Force = ………………………… N

(Total for Question 11 = 4 marks)

5


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12.

Rutherford carried out experiments in order to determine the structure of atoms.

Alpha particles, with energy of 5 MeV, were directed at thin metal foils.

Describe how these alpha-scattering experiments provided evidence for the existence and properties of the nucleus.

(5)

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(b) State and explain in the proportion of alpha particles which bounce back when the following

changes are made to the experiment.

(i) A thicker foil is irradiated with 5MeV alpha particles. (2)

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(ii) The original gold foil is irradiated with alpha particles of higher energy than 5 MeV.

(2)

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13. A low-energy particle collides elastically with a stationary particle of the same mass.The particle enters from the left of the photograph.

(a) State what is meant by collides elastically. (1)

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(b) Sketch a labelled vector diagram to show how the momentum of the initial moving

particle relates to the momenta of the two particles after the collision. (2)

(c) Use your answers to (a) and (b) to confirm that the angle between the subsequent pathsof both particles must be 90°. (2)

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(d) (i) Explain the process by which a proton is given energy in a particle accelerator. (3)

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The diagram shows a collision between a high-energy proton (track from the left) and a stationary proton in a particle accelerator experiment.

(ii) Explain why the angle between the two paths is not 90°. (2)

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(e) Deduce the direction of the magnetic field in this particle accelerator experiment.

Circle the correct direction from those given below. (1)

left to right across the paper out of the plane of the paper into the plane of the paper



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14. Bubble chambers can be used to observe the tracks of charged particles through magnetic

fields. As charged particles pass through the liquid they cause ionisation which triggers the

formation of bubbles, recording the tracks of the particles. The photograph below shows thespiral track of an electron in a bubble chamber.

(a) State whether the electron is travelling clockwise or anticlockwise. (1)

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(b) Explain why the track is curved, and why it has a spiral shape. (3)

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(b) The diagram below shows a second set of tracks, produced by an event which occurs at point X.

X

It is thought that the event which occurs at X is:

Photon electron + positron

(i) Give two ways in which the tracks are consistent with this interpretation.(2)

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(ii) Explain how this event obeys two conservation laws.

(2)

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15. In 1964 the following reaction was observed for the first time. The K particles are kaons (atype of meson) and X was a new particle.

K –

+ p K 0

+ K +

+ X

Use conservation laws to deduce the nature of particle X in order to underline the correctwords in the sentence below. Show all your working.

Particle X is a meson/baryon/lepton with a charge of – 1 / 0 / +1

(4)

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(b) Add the quark content of the proton and the K+ to the table.

Particle Quark content

K – Su

P

K 0 Ds

K +

(2)


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16. High energy particles used to investigate the structure of matter are produced in

particle accelerators. The diagram shows the main features of a linear accelerator.

(a)(i) An electron is shown between tubes B and C.

The circles on the diagram indicate the terminals of the a.c. supply. Indicate on thediagram their polarity when the electron is between tubes B and C.

Explain your answer.

(2)

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(ii) Explain why it is necessary for the tubes to increase in length along the linac.(1)

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(iii) Explain why the electrons travel with constant velocity whilst in the cylinders.

(2)

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(b) The Antiproton Decelerator at CERN slows down very high energy antiprotons to produce

anti-atoms such as anti-hydrogen.

The diagram is a representation of a hydrogen atom and an anti-hydrogen atom.

(i) Use the boxes in the diagram to identify the particles in the anti-hydrogen atom.

(ii) State one difference and one similarity between the hydrogen and anti-hydrogen atom

Difference:………………………………………………………………………………………

Similarity:………………………………………………………………………………………

(iii) State what would happen if a hydrogen atom collided with an anti-hydrogen atom.

(1)

(2)

(1)

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(iv) Explain why it is difficult to store anti-hydrogen atoms compared with anti-protons.

(2)

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(c) In the early 1960s Murray Gell-Mann proposed a quark model that consisted of three

quarks. The table gives some of the properties of these quarks.

Quark Charge Predicted mass in MeV/c

Up (u) +2/3 4

Down (d) -1/3 4

Strange (s) -1/3 80

(i) Explain what is meant by a charge of +2/3

(2)

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(ii) State the predicted mass and charge of the quark.

(2)

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(iii) Calculate the mass of the quark in kg.

(3)

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17. A cyclotron can be used to accelerate charged particles.

(a) Explain the purpose of the magnetic and electric field in a cyclotron. (5)

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(b) A beam of low-speed protons are introduced into a cyclotron.

(i) Show that the number of revolutions per second, f, completed by the protons is given by

=

2

Where e is the electronic charge, B is the uniform magnetic flux density within the cyclotron and

m is the mass of the proton.

(3)

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(ii) An alternating potential difference is placed across the two dees to increase the energy of the protons. Explain why the potential difference is used is alternating.

(2)

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(iii) Initially, whilst the proton speeds are low, the frequency at which the potential differencehas to alternate is constant. Explain how the frequency must change as the protons gain more andmore energy.

(2)

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(c) Explain why the energy of the proton cannot be increased indefinitely.

(2)

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(Total marks for test =80)


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0

0

el

e

List of data, formulae and relationships

Acceleration of free fall g = 9.81 m s−2 (close to Earth’s surface)

Boltzmann constant k = 1.38 × 10−23 J K −1

Coulomb’s law constant k = 1/4π ε = 8.99 × 109 N m2 C – 2

Electron charge e = −1.60 × 10−19 C

Electron mass m = 9.11 × 10−31 kg

Electronvolt 1 eV = 1.60 × 10−19 J

Gravitational constant G = 6.67 × 10−11 N m2 kg−2

Gravitational field strength g = 9.81 N kg−1 (close to Earth’s surface)

Permittivity of free space ε = 8.85 × 10−12 F m−1

Planck constant h = 6.63 × 10−34 J s

Proton mass m = 1.67 × 10−27 kg

Speed of light in a vacuum c = 3.00 × 108 m s−1

Stefan-Boltzmann constant σ = 5.67 × 10 – 8 W m – 2 K – 4

Unified atomic mass unit u = 1.66 × 10 – 27 kg

Unit 1

Mechanics

Kinematic equations of motion v = u + at

s = ut + ½at 2

v2 = u2 + 2as

Forces Σ F = ma g = F/m

W = mg

Work and energy ΔW = F Δ s

= ½mv2

grav = mg Δh

Materials

Stokes’ law F = 6 ηrv

Hooke’s law F = k Δ x

Density ρ = m/V

Pressure p = F/A

Young modulus E = σ/ε where

Stress σ = F/A

Strain ε = Δ x/x

Elastic strain energy E = ½ F Δ x

E

Δ E


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1 2 3

ax

Unit 2

Waves

Wave speed v = fλ

Refractive index μ = sin i/ sin r = v /v 1 2 1 2

Electricity

Potential difference V = W/Q

Resistance R = V/I

Electrical power, energy and P = VI

efficiency P = I 2 R

P = V 2/ R

W = VIt

% efficiency = useful energy output

total energy input × 100

% efficiency = useful power output

total power input × 100

Resistivity R = ρl/A

Current I = ΔQ/ Δt

I = nqvA

Resistors in series R = R + R + R

Resistors in parallel 1 = 1 + 1 + 1

Quantum physics

R R1 R2 R3

Photon model E = hf

Einstein’s photoelectric hf = o / + ½mv2

equation


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k

0

Unit 4

Mechanics

Momentum p = mv

Kinetic energy of a non-relativistic particle E = p2/2m

Motion in a circle v = ωr

T = 2[i


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Mark scheme

Question

Number

Answer Mark

1 C 1

2 A 1

3 B 1

4 C 1

5 D 16 A 1

7 B 1

8 A 1

9 C 1

10 C 1

Question

Number

Answer Mark

11.(a) opposite curvature or deflection (1) 4

11. (b) same radius or curvature (1)

11. (c) F = 0.45 x 1.6x10-19 x 1.7x107 (1)

F = 1.2x10-12 (N) (1)

Question

Number

Answer Mark

12. (a) most of the alpha particles went through undeflected/undeviated (1)

nucleus much smaller than the atom or atom is mostly empty space (1).

small proportion experience large deflection/deviation (1)

nucleus must be charged (DO NOT ACCEPT positively charged) (1)

most of the mass of atom is in the nucleus (1)

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12. (b) (i) greater proportion deflected (1)

greater chance of close approach to a nucleus (1)

12. (b) (ii) smaller proportion deflected (1)

less time spent near nuclei (1)


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Question

Number

Answer M

14. (a) anticlockwise (1) 8

14. (b) force perpendicular v (1)

force perpendicular B (1)

electron loses energy or v (1)

14. (c) (i) Any two from:

• photon leaves no track (1)

• opposite/different directions of curvatures/spiral [NOT opposite directions without

reference to curve/spiral] (1)

• similar/same curvatures/radii/shape (1)

• no evidence of any other particles/two tracks only (1)

[Symmetrical scores once under bullet point 2 or 3]

14. (c) (ii) Naming two laws e.g. charge and momentum (1)

Plus any one from:

• Q: O = (+1) + (–1) (1)

• p: p γ= pe- + pe+ (1)

• energy of photon = mass + energy of electron and positron (1)


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• L: 0 = (+1) + (-1) (1)

Question

Number

Answer Ma

15. (a) baryon (1) – 1 (1)Q: ( –1) + (+1) = (0) + (+1) + (X) (1)

B: (0) + (+1) = (0) + (0) + (X) (1)

6

15. (b) uud (1) (1)

Question

Number

Answer Ma

16. (a) (i) top terminal positive and bottom terminal negative (accept labels added to tubes C +

and B – ) (1)

electron is repelled from B and attracted to C (1)

Or (electric) field acts from C to B (1)

Or electron is repelled from – and attracted to + if the labels have been added to the

tubes (1)

18

16. (a) (ii) electron needs to be in each tube for the same time

16. (a) (iii) no electric field inside cylinders (1)

so no force (on electrons) (1)

16. (b) (i) Top box: anti-electron or positron (1)

Bottom box: anti-proton (1)

16. (b) (ii) opposite nuclear charge or similar (1)

same mass (1)

16. (b) (iii) annihilation (1)

16. (b) (iv) atoms are not charged (1)

magnetic / electric fields have no effect (1)

16. (c) (i) 2/3 charge of an electron (1)positive charge or opposite charge to electron (1)

16. (c) (ii) 4MeV/c2 (1)

+1/3 (e) (1)

16. (c) (iii) 4x106 x 1.6x10-19 (1)

divide by (3x188)2 (1)

7.1x10-30kg (1)

su


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Question

Number

Answer Ma

17. (a) Electric fields:

electric field provides force on the charge/proton (1)

gives energy to /work done / E = qV/ accelerate protons (1)

Magnetic fields:

force on moving charge/proton (1)

produces circular path/centripetal force (1)

labelled diagram showing Dees with E field indicated across gap OR B field max 3through Dees (1)

E field is reversed/alternates (1)

14

17. (b) (i) p=mv or r = mv/Be (1)v = 2πr /T or v = rω or ω = Be/m (1)

Use of f = 1/T or ω/ 2π (1)

17. (b) (ii) (protons) accelerated / given energy, in the gaps / between D’s/from one D to the other (1) every half rotation/semicircle later (polarity of D’s) needs a change (1)

17. (b) (iii) relativistic effect / v approaching c/mass increases (1)so f decreases (1)

17. (c) protons spiral outwards and hit edge (1)

B=field not strong enough/would need to increase to maintain circular motion (1)ORmass increases due to relativistic effects (1)

and f needs to change (1)

mass/energy ∞ as v c (1)

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Edexcel GCE Physics 2008 Unit 4 Topic 3 Particle Physics Test With Marks Scheme 15_16