A radiation detector in a physics laboratory measures a background count rate of 20 counts/min20\text{ counts/min}20 counts/min. A radioactive source is placed in front of the detector, and the initial reading on the detector is 340 counts/min340\text{ counts/min}340 counts/min. The half-life of this radioactive source is 18 minutes18\text{ minutes}18 minutes.
Calculate the expected reading on the detector after 54 minutes54\text{ minutes}54 minutes.
Describe how the proton number and the nucleon number of a nucleus change when it undergoes β−\beta^-β−-decay.
State one safety precaution that should be taken when handling or storing radioactive sources in a laboratory.
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.