The count rate from a radioactive isotope is recorded every 10 minutes. The count rate is corrected for background radiation.
The table shows the readings:
| Time / minutes | 0 | 10 | 20 | 30 | 40 | 50 |
|---|---|---|---|---|---|---|
| Corrected count rate / (counts s−1\text{counts}\;\text{s}^{-1}countss−1) | 1200 | 910 | 690 | 520 | 400 | 300 |
What estimate of the half-life of the isotope can be obtained from the readings in the table?
between 10 and 20 minutes
between 20 and 30 minutes
between 30 and 40 minutes
between 40 and 50 minutes
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.