Uses of nuclear radiation (physics only) - AQA GCSE Physics Exam Questions

Practise 23 exam-style questions on Uses of nuclear radiation (physics only) for AQA GCSE Physics. Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.

23 questions
1–6 marks each
Instant marking
No sign-up needed

20 questions, marked as you go

Sample questions with model answers

Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.

Question 1

2 marks

Explain why a medical tracer used to explore an internal organ should emit gamma rays rather than alpha particles.

Model answer

Gamma rays are penetrating enough to pass out of the body, so they can be detected by a camera outside. Alpha particles would be absorbed inside the body, so they could not be detected, and because they are strongly ionising they would damage the cells around the organ.

Explanation

A tracer must be detectable from outside and cause as little harm as possible. Gamma rays meet both needs because they are penetrating and only weakly ionising.

Mark scheme

1 mark
gamma rays can pass out of the body to be detected outside
1 mark
alpha particles would be absorbed inside the body (so could not be detected) and, being strongly ionising, would damage cells
allow either idea for the mark

Question 2

2 marks

A patient is injected with technetium-99m, a tracer with a half-life of 6 hours. The activity at the time of injection is 400 MBq.

Calculate the activity of the technetium-99m 24 hours later.

Model answer

Number of half-lives = 24 ÷ 6 = 4
400 → 200 → 100 → 50 → 25
Activity = 25 MBq

Explanation

After 4 half-lives the activity is 1/16 of its starting value. The short half-life is one reason technetium-99m is such a widely used tracer: the patient's exposure falls quickly after the scan.

Mark scheme

1 mark
24 ÷ 6 = 4 half-lives
an answer of 25 (MBq) scores 2 marks
1 mark
25 MBq
allow 400 → 200 → 100 → 50 → 25 shown

Question 3

3 marks

For a bone scan, a patient is injected with a gamma-emitting tracer that collects in bone, especially where bone cells are growing quickly, such as in a tumour.

Explain how the image from the gamma camera can show where a tumour is.

Model answer

The tracer travels around the body in the blood and is absorbed by the bones. More of it collects where bone cells are growing quickly, such as in a tumour. More gamma rays come from that area, so the gamma camera shows it as a bright "hot spot" on the image, revealing where the tumour is.

Explanation

Tracer scans show how organs are working, not just their shape. Areas that take up more tracer emit more gamma rays and appear brighter on the image.

Mark scheme

1 mark
the tracer is carried around the body in the blood and absorbed by the bones
1 mark
more of the tracer collects in the tumour (where bone is growing quickly)
1 mark
more gamma rays are emitted from there, so the tumour shows up as a bright spot / hot spot on the image

Question 4

5 marks

A doctor recommends a CT scan of a patient's abdomen to find the cause of severe pain. The scan gives a radiation dose of 10 mSv. The patient is worried about the risk.

The risk of a fatal cancer caused by radiation is about 1 in 20 000 for each mSv of dose. The average natural background dose is 2.7 mSv per year.

Calculate the risk from the scan, and evaluate whether the patient should have it.

Model answer

Risk = 10 × 1/20 000 = 10/20 000 = 1 in 2000
This is a small risk: there is a 1999 in 2000 chance that the scan causes no harm. The dose is the same as about 10 ÷ 2.7 = 3.7 years of natural background radiation. Severe pain may be caused by a serious illness, and not finding the cause could be far more dangerous than the scan. The benefit outweighs the small risk, so the patient should have the scan.

Explanation

Evaluating a perceived risk means calculating the actual risk from the data, comparing it with familiar risks, and weighing it against the consequences of not having the procedure.

Mark scheme

1 mark
risk = 10 × 1/20 000
max 5; correct answer with no working scores full marks
1 mark
= 1 in 2000
allow 0.0005 / 0.05%
1 mark
the risk is small: a 1999 in 2000 chance of no harm
1 mark
the dose is equal to about 3.7 years of natural background radiation
1 mark
the benefit of finding the cause of severe pain (possibly a serious illness) is large / not having the scan could be more dangerous
1 mark
conclusion: the benefit outweighs the risk, so the patient should have the scan

Ready to try the rest? Every answer you write is marked against the mark scheme, so you can see exactly where the marks are.

AI Tutor Hints first, answers after you try

Hi! Stuck? Ask me for a hint and I’ll help you work it out. Once you’ve checked your answer I can explain exactly where the marks are.