A level: Radioactivity Questions
Q18.
(a) Which of the following forms of ionizing radiation produces the greatest number of ion pairs per mm in air? (Tick the correct answer)
α particles
|
|
| β particles |
|
| γ rays |
|
| X-rays |
|
[1 mark]
(b)
(i) Complete the table below showing the typical maximum range in air for α and β particles.
Radiation Type |
Typical maximum range in air /m |
α |
|
β |
|
[2 marks]
(ii) γ rays have a range of at least 1 km in air.
However, a γ ray detector placed 0.5 m from a γ ray source detects a noticeably smaller count-rate as it is moved a few centimetres further away from the source.
Explain this observation.
[1 mark]
(c) Following an accident, a room is contaminated with dust containing americium (which is an α-emitter). Explain the most hazardous aspect of the presence of this dust to an unprotected human entering the room.
[2 marks]
(Total 6 marks)
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