A technician monitors microwave radiation at the control point of an industrial dryer during two trial runs.
For each run, the exposure value is calculated by multiplying the relative intensity by the duration in minutes. The action level is an exposure value of 20. If the exposure value is greater than the action level, the shielding must be checked.
| Run | Relative intensity at the control point | Duration in minutes |
|---|---|---|
| R | 6 | 3 |
| S | 3 | 8 |
Which statement is correct?
Run S exceeds the action level, so covering clothing should be used because microwaves damage surface-cell DNA.
Neither run exceeds the action level, so no shielding check is needed because microwaves are non-ionising.
Run S exceeds the action level, so the shielding should be checked because microwaves can cause internal heating.
Run R exceeds the action level, so the shielding should be checked because its microwave intensity is higher.
104 exam-style questions on Edexcel GCSE Physics 5.4 Uses and dangers of EM radiation, covering 5.4.1 Dangers of electromagnetic radiation, 5.4.2 Uses of electromagnetic radiation, 5.4.3 Radio waves and oscillations in circuits, and 5.4.4 Changes in atoms and nuclei generating radiation. Each one has a worked solution and a mark scheme showing where the marks go.