A radioactive sample contains N N\,N parent nuclei at a given time. The isotope has a half-life T1/2T_{1/2}T1/2. The rate of decay of this sample is proportional to:
NT1/2\dfrac{N}{T_{1/2}}T1/2N
NT1/2N T_{1/2}NT1/2
T1/2N\dfrac{T_{1/2}}{N}NT1/2
N2T1/2N^2 T_{1/2}N2T1/2
128 exam-style questions on AQA A Level Physics Radioactivity (A-level only), covering Rutherford scattering (A-level only), $\alpha$ , $\beta$ and $\gamma$ radiation (A-level only), Radioactive decay (A-level only), Nuclear instability (A-level only), Nuclear radius (A-level only), Mass and energy (A-level only), Induced fission (A-level only), and Safety aspects (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.