Particle Physics
Definitions: Particle Physics
- One exam question, the mark-scheme answer, and the exact phrases that score (highlighted, then listed below in the same colour).
Exam question
State what is meant by the proton number and by the nucleon number.
Model answer
The proton number is the number of protons; the nucleon number is the total number of protons and neutrons.
Marking points
1 mark each- 1number of protons(1)
- 2total number of protons and neutrons(1)
Exam question
State what is meant by isotopes.
Model answer
Isotopes have the same number of protons but different numbers of neutrons.
Marking points
1 mark each- 1same number of protons but different numbers of neutrons(1)
Exam question
State the quark composition of a proton and of a neutron, and show the charges add up.
Model answer
A proton is up, up, down (uud); a neutron is up, down, down (udd). The charges add up: u is and d is , so uud gives and udd gives 0.
Marking points
1 mark each- 1up, up, down (uud)(1)
- 2up, down, down (udd)(1)
Exam question
State what is meant by a fundamental particle.
Model answer
A fundamental particle cannot be split into smaller particles.
Marking points
1 mark each- 1cannot be split into smaller particles(1)
Exam question
State what is meant by a hadron and by a lepton.
Model answer
A hadron: made of quarks. A lepton: not made of quarks.
Marking points
1 mark each- 1hadron: made of quarks(1)
- 2lepton: not made of quarks(1)
Exam question
State what is meant by an antiparticle.
Model answer
An antiparticle has the same mass but opposite charge.
Marking points
1 mark each- 1same mass but opposite charge(1)
Exam question
State the particles emitted in beta-minus decay and in beta-plus decay.
Model answer
In β⁻ decay: an electron and an (electron) antineutrino. In β⁺ decay: a positron and a neutrino.
Marking points
1 mark each- 1an electron and an (electron) antineutrino(1)
- 2a positron and a neutrino(1)