Key Points: 2. Particles and Radiation: Paper 1: Physics A Level AQA

Charge

Always indicated by the particle.

Baryon number

0 except for baryons which are +1

L_μ

0 except for a muon and muon neutrino which are +1

L_e

0 except for an electron and electron neutrino which are +1

photocell

A photocell also shows the photoelectric effect. UV radiation is incident on the negatively charged plate which allows electrons to flow to the positive cathode.

Excitation

Is the movement of electrons up to a higher energy level; either an electron collides with the orbital electron or a photon is absorbed by it, transferring energy to it. When the electron de-excites, it moves down in energy levels and emits a photon.

Ionisation

Is when an electron is removed from an atom