AQA GCSE Combined Science: Synergy · 8465
Specification 4.3.2.3 · Paper 1, Paper 2
Revise: Half-LifeThe half-life of a radioactive isotope is the average time taken for the number of nuclei of that isotope in a sample to halve. It can also be defined as the average time taken for the sample's count rate to fall to half its initial level.