A radioactive source is placed 15 mm in front of a detector.
The count rate from the source is 3000 counts/minute3000\text{ counts/minute}3000 counts/minute.
With a thin sheet of paper between the source and the detector, the count rate is 1800 counts/minute1800\text{ counts/minute}1800 counts/minute.
With a sheet of aluminium 5 mm thick between the source and the detector, the count rate is 0 counts/minute0\text{ counts/minute}0 counts/minute.
Which radioactive emissions are coming from the source?
alpha, beta and gamma
alpha and beta only
beta and gamma only
alpha and gamma only
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.