A radioactive material, YYY, has a half-life of 3 minutes. At the beginning of an experiment, a sample of the material produces a count-rate of 640 counts/s.
Determine the expected count-rates from this sample at: (i) t=6t = 6t=6 minutes, (ii) t=15t = 15t=15 minutes.
Using the radioactive decay relationship: (i) Calculate the expected count-rate from the sample after 7.5 minutes. (ii) Find the time it takes for the count-rate of the sample to fall from 500 counts/s to 250 counts/s.
A second sample of this same radioactive material YYY gives an initial count-rate of 320 counts/s. What is the half-life of this second sample?
To track the flow of water in deep underground pipelines and locate leaks, a radioactive isotope is added to the water. (i) Explain why the radioactive material YYY is not suitable for this application. (ii) State two other properties (excluding half-life) that a radioactive material must have to be suitable for detecting leaks in underground pipelines.
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.