OCR · A-Level · Physics
Course version: H556 · Version from Sept 2015
(d) classification of leptons; electron and neutrino as examples of…
Full specification wording
Fundamental particles: (d) classification of leptons; electron and neutrino as examples of leptons; all leptons are subject to the weak nuclear force but not the strong nuclear force
Leptons are fundamental particles that do not experience the strong nuclear force.
Checked against the OCR H556 specification (opens in a new tab) on .
- Point 4 of 12
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Leptons are fundamental particles that do not experience the strong nuclear force. The electron and the neutrino are examples of leptons. All leptons are subject to the weak nuclear force, which is responsible for processes such as beta decay. Leptons are not made of quarks. In MCQs, you may be asked to identify a lepton from a list, or to state which forces act on leptons. Remember that there are three flavours of charged lepton (electron, muon, tau) and corresponding neutrinos, but the specification only requires electron and neutrino as examples.
What earns the marks
- Leptons are fundamental particles.
- Electron and neutrino are examples of leptons.
- All leptons are subject to the weak nuclear force.
- Leptons are not subject to the strong nuclear force.
- Leptons are not made of quarks.
- Lepton number is conserved in interactions.
Common mistakes and how to put them right
Thinking leptons feel the strong force.
Put it right: They do not, because they are not made of quarks.
Believing neutrinos are hadrons.
Put it right: Neutrinos are leptons and are fundamental.
Assuming all leptons are charged.
Put it right: Neutrinos are neutral leptons.
Confusing lepton number with baryon number.
Put it right: They are separate conservation laws.
Exam tips
- Learn the definition: leptons are fundamental particles that do not feel the strong force.
- Remember electron and neutrino as the required examples.
- In MCQs, if a particle is not made of quarks and does not feel the strong force, it is a lepton.
Try the lesson
The start of the Fundamental particles: (d) classification of leptons; electron and neutrino as examples of leptons; all leptons are subject to the weak nuclear force but not the strong nuclear force lesson, made from checked teaching notes for this specification point.
Listen
Leptons are fundamental particles that do not experience the strong nuclear force. The electron and the neutrino are examples of leptons. All leptons are subject to the weak nuclear force, which is responsible for processes such as beta decay. Leptons are not made of quarks. In MCQs, you may be asked to identify a lepton from a list, or to state which forces act on leptons. Remember that there are three flavours of charged lepton (electron, muon, tau) and corresponding neutrinos, but the specification only requires electron and neutrino as examples. A strong answer earns marks for these points. Leptons are fundamental particles. Electron and neutrino are examples of leptons. All leptons are subject to the weak nuclear force. Leptons are not subject to the strong nuclear force. Exam tip: Learn the definition: leptons are fundamental particles that do not feel the strong force.
See it
Key words
Say what each word means before you turn the card.
Weak nuclear force
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Lepton number conservation
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Particle classification
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See every definition
- Weak nuclear force
- A force to which all leptons are subject, and which is responsible for processes such as beta decay.
- Lepton number conservation
- Lepton number is conserved in interactions, and it is a separate conservation law from baryon number.
- Particle classification
- Leptons are classified as fundamental particles that do not feel the strong force, with the electron and neutrino as examples.
Label the diagram
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1Box 1
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3Box 3
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