The count rate from a sample of radioactive material is measured every 15 minutes for 1.5 hours.
The results, suitably corrected for background radiation, are shown in the table below:
| Time / min\text{min}min | 0 | 15 | 30 | 45 | 60 | 75 | 90 |
|---|---|---|---|---|---|---|---|
| Count rate / counts/s\text{counts/s}counts/s | 400 | 295 | 220 | 165 | 120 | 90 | 65 |
Suggest one possible source for the background radiation.
Name the two types of particle that the radioactive material might be emitting.
From the table, without attempting a graph, estimate the half-life of the radioactive material.
A similar experiment is carried out, using a smaller quantity of the same radioactive material. State what effect, if any, this has on: (i) the count rate readings in the table, (ii) the half-life of the material.
State one precaution that should be taken for safe handling of the radioactive material.
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.