At a steel mill, an engineer services a thickness gauge containing a sealed gamma source. After the service, the source remains in the workshop and the engineer leaves.
On another occasion, a damaged gauge releases loose radioactive material into the engineer's tool case. The engineer carries the tool case out of the workshop.
Explain why leaving the workshop ends the engineer's exposure in the first incident but may not end the exposure in the second incident.
97 exam-style questions on Edexcel GCSE Physics 6.5 Uses and dangers of radioactivity, covering 6.5.1 Uses of radioactivity, 6.5.2 Dangers of ionising radiation and precautions, 6.5.3 Half-life and radiation dangers, 6.5.4 Safety precautions for radiation exposure, and 6.5.5 Contamination and irradiation. Each one has a worked solution and a mark scheme showing where the marks go.