Decay (Also seen in GCSE Physics 1)

Something that is radioactive will decay into something that is stable. Radioactive decay happens randomly and spontaneously: there is no way of predicting when a radioactive nucleus will decay and external factors do not influence it at all (e.g. pressure and temperature).

What we can do is give a probability that a nucleus will decay in a given time.

Decay Constant, l

Every radioactive isotope has its own probability that a nucleus will decay, called the decay constant.

Activity, A

The activity of a radioactive source is the number of decays that happen every second.

1 becquerel is equal to one decay per second, 50 becquerels is equal to 50 decay per second,

Activity is measured in becquerels, Bq (decays per second, s^-1)

During a certain amount of time, Δt, some radioactive atoms (ΔN) decay from a sample of N atoms.