When a radioactive isotope is set up close to a radiation detector, a count rate of 64 000 counts/s64\,000\text{ counts/s}64000 counts/s is obtained. The table shows the count rate from the isotope over a three-year period:
| Time / years | Count rate / counts/s\text{counts/s}counts/s |
|---|---|
| 0 | 64 00064\,00064000 |
| 1 | 48 00048\,00048000 |
| 2 | 36 00036\,00036000 |
| 3 | 27 00027\,00027000 |
What is the half-life of the isotope?
less than 1 year
more than 1 year but less than 2 years
more than 2 years but less than 3 years
more than 3 years
144 exam-style questions on CIE IGCSE Physics 5.2.4a Half-life. Each one has a worked solution and a mark scheme showing where the marks go.