Physics (AS & A Level) · May / June 2020 · Paper 43 · Question 11

An electron, at rest, has mass me and charge –q. A positron is a particle that, at rest, has mass me and charge +q. A positron interacts with an electron. The electron and the positron may be considered to be at rest. The outcome of this interaction is that the electron and the positron become two gamma-ray (γ-ray) photons, each having the same energy.

Read automatically from the paper; the printed page above is exact.