Uses of radioactivity

Question 1

Use for alpha

Answer 1

smoke alarms

Question 2

How do smoke alarms work?

Answer 2

Smoke detectors contain a weak source of alpha radiation. This ionises air inside the alarm and creates a very small electric current. When smoke enters the alarm, this current drops, setting off the alarm. If there is no smoke, there is no change in current and so the alarm stays quiet.

Question 3

Use for beta

Answer 3

paper mills

Question 4

How do paper mills work?

Answer 4

In paper mills, sheets of paper pass between a beta source and a detector which counts them. Some beta particles don’t get through the paper. The thicker the paper, the fewer get through and so the counts recorded by the counter go down. If the counts fall too low, this shows that the paper is too thick and so the rollers squeeze together.

Question 5

Use for gamma

Answer 5

medical tracers

sterilising equipment

Question 6

How do medical tracers work?

Answer 6

A weak source of gamma rays is either swallowed by or injected into a patient. Gamma rays travel out of the body and special cameras are used to monitor the flow of the source around the body. Doctors can then identify problems such as blockages or leaks within internal organs. A similar technique can also be used to detect leaks in underground pipes.

Question 7

What is a gamma knife?

Answer 7

Device that focuses many separate beams of gamma rays onto a brain tumour, giving it a much larger dose than the surrounding tissue

Question 8

How does a gamma knife work?

Answer 8

Gamma rays are fired into the body and focused on the tumour. The source is moved around in order to reduce the exposure of the healthy tissue but provide a high enough dose to kill the cells inside the tumour.