Alpha, beta and gamma radiationAQA A-Level Physics: Mind map

Exam questions on Alpha, beta and gamma radiation

1. A factory makes aluminium foil in a continuous strip. A radioactive source is placed on one side of the strip and a Geiger–Müller (GM) tube on the other side. The count rate at the detector is monitored by a computer, which adjusts the rollers that set the thickness of the foil.
   Explain why a gamma source would not be suitable for monitoring the thickness of the aluminium foil.2 marks
2. A student investigates how the count rate from a gamma source varies with distance. With no source present, a Geiger–Müller (GM) tube records an average of 24 counts per minute. With the source 0.10 m from the tube, the GM tube records 664 counts per minute.
   The student subtracts 24 counts per minute from every reading. Explain why, and give two sources of the radiation responsible for this count.2 marks
3. A hospital technician handles a sealed gamma source. At a distance of 0.50 m from the source, the gamma intensity is 80 μW m⁻². The source can be treated as a point source in air.
   Calculate the intensity of the gamma radiation at a distance of 2.0 m from the source.3 marks