A student is using a Geiger-Müller (GM) tube connected to a counter to measure the radiation emitted by a radioactive source.
The count rate, measured over three successive minutes, gives values of:
Explain why a variation like this is to be expected in such an experiment.
The radioactive source is then put into its lead container and returned to its secure storage. A further measurement is taken over one minute, giving a reading of 24 counts/minute24\text{ counts/minute}24 counts/minute.
State the name used for the radioactivity being detected during this minute.
Suggest two possible natural sources for this radioactivity.
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.