BRAINCAKEThe Weak Interaction
There are four fundamental interactions: gravitational, electromagnetic, strong and weak. The weak interaction (the weak nuclear force) is responsible for beta decay.
Key features of the weak interaction:
• It acts on both quarks and leptons. The strong interaction acts only on quarks (hadrons), not on leptons.
• It is the only interaction that can change one type (flavour) of quark into another, for example d → u.
• It has a very short range, about 10−18 m, much shorter than the strong interaction (about 3 fm).
• It is much weaker than the strong and electromagnetic interactions, which is why beta decays can have long half-lives.
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Key terms in this lesson
- quark
- A fundamental particle that combines with others, bound by the strong nuclear force, to form hadrons such as protons and neutrons.
- lepton
- A fundamental particle, such as the electron or neutrino, that does not feel the strong nuclear force.
More in Fundamental Particles
- Hadrons and Leptons
- The Strong Nuclear Force
- Quarks and Antiquarks
- Quark Composition of Protons and Neutrons
- Baryons and Mesons
- Beta-Minus Decay and Quarks
- Beta-Plus Decay and Quarks
- Conservation of Charge, Baryon Number and Lepton Number
All 11 lessons in Fundamental Particles · All OCR A-level Physics topics