A physicist uses a radiation detector to measure the activity of a radioactive sample.
The initial measurement displays a count rate of 1200 counts/min. After a period of 20 hours, the physicist takes another measurement and records a count rate of 75 counts/min.
Calculate the half-life of the radioactive sample.
144 exam-style questions on CIE IGCSE Physics 5.2.4a Half-life. Each one has a worked solution and a mark scheme showing where the marks go.