Mesons, baryons and leptons
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The teaching part (1 min) is free to watch. A free account opens the whole lecture: 3 practice questions, 4 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- Sorting the particle zoo
- The families
Read the transcript of the teaching part
Last time
Before we start: last time, in Isotopes, alpha and beta particles, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
Sorting the particle zoo
By the 1960s, physicists had found hundreds of particles. It looked like chaos until the quark model sorted them into a few families. Two big groups: the hadrons, made of quarks, and the leptons, which are fundamental. Within hadrons, baryons and mesons.
The families
Hadrons are made of quarks. They feel the strong interaction. A baryon has three quarks, or three antiquarks. Protons and neutrons are baryons. A meson has one quark and one antiquark. Leptons are fundamental. They are the electron, the positron, the neutrino and the antineutrino.
Chapter 11.3: Particle physics
- Quarks, antiquarks and hadron charges 5 min
- Mesons, baryons and leptons 5 min
Also for A Level Physics 9702
Which topics come up most in A Level Physics 9702 past papers, counted from every paper since 2004: Paper 1 topic frequency, Paper 2 topic frequency.