Oxford AQA International A-level · Physics (9630)

Elementary particles: Practice Questions

5 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Elementary particles.

10 questions31 marksFree, no account

Question 1

1 mark

Which of the following statements correctly compares an electron and its antiparticle, the positron?

Question 2

1 mark

Which of the following statements correctly compares an electron and its antiparticle, the positron?

Question 3

1 mark

A gamma-ray photon undergoes pair production to create a particle and its antiparticle. If the rest energy of the particle produced is \( 105.7 \text{ MeV} \), what is the minimum frequency of the photon required?

Take Planck's constant \( h = 6.63 \times 10^{-34} \text{ J s} \) and \( 1 \text{ eV} = 1.60 \times 10^{-19} \text{ J} \).

Question 4

1 mark

The rest energy of a proton is approximately \(938\text{ MeV}\). What is the minimum energy of a single photon required to produce a proton-antiproton pair through the process of pair production?

Question 5

1 mark

Which of the following describes the conservation of baryon number and lepton number during the beta-plus (\(\beta^+\)) decay of a proton?
The decay is represented as: \(p \rightarrow n + e^+ + \nu_e\)

Question 6

3 marks

Explain why a particle and its corresponding antiparticle must produce at least two photons when they undergo annihilation.

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Question 7

5 marks

Calculate the minimum energy required, in MeV, for a single gamma-ray photon to produce a proton-antiproton pair, given the rest energy of a proton is \(938 \text{ MeV}\).

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Question 8

6 marks

A hypothetical decay is proposed where a neutron transforms into a positron and an antiproton. By evaluating the conservation of charge, baryon number, and lepton number, explain why this process is strictly forbidden by the laws of particle physics.

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Question 9

5 marks

(a) Describe the process of pair production and explain why there is a minimum photon energy required for this process to occur.

(b) A photon with energy \(1.50\) MeV interacts with a nucleus to produce an electron-positron pair. Calculate the maximum kinetic energy of the electron produced, assuming the energy is shared equally between the two particles.
(Rest energy of an electron = \(0.511\) MeV)

(c) State the name of the antiparticle for each of the following:
i) Proton
ii) Neutrino

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Question 10

7 marks

(a) Define annihilation and describe what happens when a proton meets an antiproton.

(b) Calculate the frequency of each of the two identical photons produced when a proton and an antiproton annihilate. Assume both particles are initially at rest.
Rest energy of a proton = \(938\) MeV.
Planck constant \(h = 6.63 \times 10^{-34}\) J s.
Elementary charge \(e = 1.60 \times 10^{-19}\) C.

(c) Discuss how the laws of conservation of baryon number and conservation of lepton number apply to this annihilation interaction.

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