A rolling mill uses a gamma thickness gauge to monitor steel strip. The detector count rate remains below the target value. Checks rule out any change in source activity or in the positions of the source and detector. Increasing the hydraulic rolling force reduces the thickness of the strip.
Which action should the automatic control system take?
Reduce the rolling force until the detector count rate rises to the target value.
Reduce the rolling force because the low count rate shows that the strip is too thin.
Increase the rolling force until the detector count rate rises to the target value.
Keep the rolling force unchanged because gamma radiation is unaffected by the steel thickness.
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.