A student measures the activity of a radioactive isotope with a very long half-life. They record the number of counts detected in consecutive 10-second intervals and record the data in the table below.
| Time interval / s | Number of counts detected |
|---|---|
| 0 to 10 | 32 |
| 10 to 20 | 41 |
| 20 to 30 | 28 |
| 30 to 40 | 35 |
| 40 to 50 | 44 |
The student notices that the number of counts fluctuates significantly between each interval and thinks they made an error during the measurements.
The physics teacher explains that these fluctuations are expected.
Justify the teacher's explanation.
90 exam-style questions on Edexcel GCSE Physics 6.3 Nuclear equations and decay. Each one has a worked solution and a mark scheme showing where the marks go.