GCSE Questions: Radioactivity


(a) The diagram shows a radiation detector and counter being used to measure background radiation. The number shows the count ten minutes after the counter was reset to zero.

(i) Name one source of background radiation.

(1 mark)

(ii) Calculate the average background radiation level, in counts per second. Show clearly how you work out your answer.

(2 marks)

(b) The detector and counter are used in an experiment to show that a radioactive source gives out alpha and beta radiation only.

Two different types of absorber are placed one at a time between the detector and the source.

For each absorber, a count is taken over ten minutes and the average number of counts per second worked out.

The results are shown in the table below.

Absorber used Average count per second
No absorber 33
Card 1 mm thick 20
Metal 3 mm thick 2


Explain how these results show that alpha and beta radiation is being given out, but gamma radiation is not being given out.

(3 marks)

(Total 6 marks)