Exam tip 1
Pay close attention to the conservation laws in nuclear reactions. Always check that the total charge, nucleon number, and lepton number are balanced on both sides of a decay equation for both Paper 1 and Paper 2 questions.
9702 · 11.2
Fundamental particles — common mistakes
Common exam mistakes on 9702 Fundamental particles. Learn what loses marks, then practise the topic with Examiner’s Ink.
What is the main difference between a quark and a lepton?
Quarks experience the strong nuclear force and combine to form hadrons (like protons and neutrons), whereas leptons (like electrons) do not experience the strong force and are fundamental particles on their own.
Why is the unified atomic mass unit (u) used instead of kilograms for atomic masses?
The unified atomic mass unit provides a more convenient and practical scale for expressing the masses of atoms and subatomic particles, which are extremely small when measured in kilograms. It simplifies calculations and comparisons in nuclear physics.
How do alpha and beta particles differ in terms of their energy spectra?
Alpha particles are emitted with discrete, specific energies because the decay energy is split cleanly between the alpha particle and the recoiling nucleus. Beta particles, however, have a continuous energy spectrum because the decay energy is shared between the beta particle and an accompanying neutrino (or antineutrino).
What are the four fundamental forces of nature, from strongest to weakest?
The four fundamental forces are the Strong Nuclear Force, the Electromagnetic Force, the Weak Nuclear Force, and the Gravitational Force.