# A-level Physics (Advancing Physics)/Leptons/Worked Solutions

1. An electron is produced by a nuclear reaction, but an electron-antineutrino is not produced. What other particle is produced?

A positron, since this is the only other first-generation particle with a lepton number of -1.

2. Why do electrons not make up part of the nucleus?

Electrons do not interact with the strong nuclear force.

3. Why did it take until the 1950s to detect the first antineutrino?

They are tiny, chargeless, and almost massless.

4. Complete the following equation for the emission of a beta particle from a nucleus:

${\displaystyle _{0}^{1}n\to _{1}^{1}p\;+\;_{-1}^{0}e^{-}\;+\;_{0}^{0}{\bar {\nu }}_{e}}$

5. Complete the following equation for the emission of an antielectron from a nucleus:

${\displaystyle _{1}^{1}p\to _{0}^{1}n\;+\;_{1}^{0}e^{+}\;+\;_{0}^{0}\nu _{e}}$

6. Complete the following equation for the capture of an electron by a nucleus:

${\displaystyle _{1}^{1}p+\;_{-1}^{0}e^{-}\to _{0}^{1}n\;+\;_{0}^{0}\nu _{e}}$