A sterilisation plant compares four settings for a gamma source. A dose of at least 24 units is needed to sterilise the equipment. Dose equals dose rate multiplied by exposure time.
| Setting | Dose rate in units per minute | Exposure time in minutes |
|---|---|---|
| P | 4 | 5 |
| Q | 6 | 4 |
| R | 8 | 2 |
| S | 10 | 3 |
Which setting sterilises the equipment using the lowest sufficient dose?
setting Q
setting P
setting R
setting S
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.