A maintenance worker passes through three work areas near an active microwave communications aerial. A monitor measures the microwave intensity at the worker's position.
The monitor calculates a total exposure reading by multiplying the microwave intensity by the time spent in each work area and adding the results for all the areas.
Using intensity in W m−2\mathrm{W\,m^{-2}}Wm−2 and time in seconds gives an exposure reading in J m−2\mathrm{J\,m^{-2}}Jm−2.
| Work area | Microwave intensity in W m−2\mathrm{W\,m^{-2}}Wm−2 | Time spent in area in minutes |
|---|---|---|
| inspection area | 12 | 3.0 |
| adjustment area | 5.0 | 8.0 |
| final test area | 15 | to be calculated |
The maximum total exposure reading set for this task is 9.0 kJ m−29.0\,\mathrm{kJ\,m^{-2}}9.0kJm−2.
Calculate the greatest time the worker can spend in the final test area without exceeding the maximum total exposure reading.
Explain how exposure to microwaves could harm the worker.
Suggest one additional precaution that would reduce the worker's exposure without reducing the time spent in the work areas.
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.