Topic 6 - Uses Of Radioactivity

Question 0

Uses of beta rays

Answer 0

Used in paper thickness gauges

Question 1

Uses of gamma rays

Answer 1

To find any leaks in pipes

Radiotherapy to cure cancer

Sterilises food and equipment

Tracers in medicine

Question 2

Uses of alpha rays

Answer 2

Smoke alarms

Question 3

How do gamma rays work in pipes to find leaks?

Answer 3

Gamma can penetrate the Earth above the pipe

Question 4

Method of finding a leak in a pipe

Answer 4

• radioactive isotope injected into pipe
• area above ground checked with a Geiger Counter to monitor levels of radioactivity
• a higher reading than other areas indicates a leak in pipe
• this small area can be evacuated and the pipe fixed

Question 5

Why can’t beta and alpha be used when finding a leak in a pipe

Answer 5

Beta and Alpha would be absorbed by the Earth before reaching the detector

Question 6

How is beta used in paper thickness gauges?

Answer 6

The penetration of beta through aluminium or paper is affected by its thickness

Question 7

Method of a paper thickness gauge

Answer 7

• beta particles fired through the paper and detected by Geiger Counter
• if count rate too high, the paper is too thin so the rollers move apart to make the paper thicker and vice verse

Question 8

Why can’t gamma and alpha be used in the paper thickness gauge process?

Answer 8

Alpha - all the alpha particles would be stopped by the thickness of the paper or aluminium, so nothing detected on other side

Gamma - gamma particles would not be affected by thickness, so the count rate would stay the same for all the thicknesses

Question 9

How is alpha used in smoke alarms?

Answer 9

Alpha particles are absorbed by smoke particles

Question 10

What happens in smoke alarms?

Answer 10

• Alpha particles emitted and ionise the air particles inside the smoke alarm. This allows the air to conduct electricity and a current flows in a circuit
• any smoke particles absorb the alpha particles - less ionisation of air particles - so air cannot conduct electricity easily, less current in circuit. This sets off alarm

Question 11

Why gamma and beta particles not used in smoke alarms?

Answer 11

• gamma and beta penetrate smoke particles

- therefore the smoke particles wouldn’t affect the ionisation of air particles and the alarm would not sound

Question 12

How do gamma rays sterilise food?

Answer 12

Gamma rays can pass straight through the food and packaging

Question 13

What is a beta particle

Answer 13

Fast moving electron

Question 14

Two uses of radioactivity

Answer 14

Smoke alarms

Irradiating food