Question 1Multiple choice · 1 markA* challenge
Which particle is a fundamental particle?
- A pion
- B proton
- C neutron
- D electron
Show answer
Answer: D
Free Particle physics questions for AS Level Physics (9702), part of Waves, electricity & particles. Each question has the answer and the marking points an examiner would look for.
Generate a full Particle Physics worksheet →All Waves, electricity & particles questionsWhich particle is a fundamental particle?
Answer: D
What is the quark composition of a neutron?
Answer: C
Which term is described by this statement?
“A fundamental particle not made of quarks, such as an electron.”
Answer: C
A nucleus of ²³⁸₉₂U decays to ²⁰⁶₈₂Pb by a series of α and β− decays.
Determine the number of α-particles and β− particles emitted.
| Part | Answer and marking points | Marks |
|---|---|---|
| 8 α; 6 β nucleon number falls by 32, so 8 α B1 proton number would fall by 16 but falls by 10 M1 6 β− A1 | 3 |
The proton and the neutron are made of quarks.
State the quark composition of a proton and of a neutron.
Describe β− decay in terms of quarks, and name the leptons emitted.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | uud; udd proton: uud B1 neutron: udd B1 | 2 |
| (b) | d → u + e− + ν̄ a down quark changes to an up quark B1 an electron is emitted B1 and an electron antineutrino B1 | 3 |
This question is about particles and the nucleus.
State the quark composition of a proton and of a neutron.
Show that the charge of a proton is +e using the charges of its quarks.
During β− decay a neutron changes into a proton. Describe the change in quark composition and name the other particles emitted.
Explain why the existence of the antineutrino was proposed, by referring to the energy spectrum of β particles.
In the α-particle scattering experiment, a very small proportion of α-particles were deflected through more than 90°. Explain what this shows about the nucleus.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | uud; udd proton: up, up, down B1 neutron: up, down, down B1 | 2 |
| (b) | +2/3 + 2/3 − 1/3 = +1 (+23) + (+23) + (−13) = +1 (e) B1 | 1 |
| (c) | a down quark changes to an up quark; electron and electron antineutrino emitted a down quark changes into an up quark B1 an electron (β−) is emitted B1 and an electron antineutrino B1 | 3 |
| (d) | β particles have range of energies; another particle carries the remaining energy beta particles are emitted with a continuous range of kinetic energies B1 so a third particle must carry away the remaining energy (and momentum) B1 | 2 |
| (e) | nucleus very small; contains most of the mass and is positively charged the positive charge and most of the mass are concentrated in a very small nucleus B1 strong repulsion only when an α-particle passes very close B1 | 2 |
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