A radioactive isotope has a half-life of 50 s. The activity, AAA, of a sample of this isotope is measured at a certain time. What was the activity of the sample 100 s earlier?
A4\frac{A}{4}4A
A2\frac{A}{2}2A
2A2A2A
4A4A4A
484 exam-style questions on CIE IGCSE Physics 5.2 Radioactivity, covering 5.2.1 Background radiation and measuring count rate, 5.2.2a Alpha, beta and gamma emission, 5.2.2b Deflection and ionising effects of nuclear radiation, 5.2.3a Radioactive decay, 5.2.3b Effects of decay on the nucleus and decay equations, 5.2.4a Half-life, 5.2.4b Choosing isotopes for applications, and 5.2.5 Effects of ionising radiation and safety precautions. Each one has a worked solution and a mark scheme showing where the marks go.