Background radiation (physics only) - AQA GCSE Physics Exam Questions

Practise 24 exam-style questions on Background 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.

24 questions
1–6 marks each
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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

Name two natural sources of background radiation.

Model answer

Rocks such as granite (including the radon gas they release), and cosmic rays from space.

Explanation

Natural background radiation comes from radioactive isotopes in rocks, soil, air (radon), food and our bodies, and from cosmic rays arriving from space. Natural sources make up most of the average person's dose.

Mark scheme

1 mark
rocks (e.g. granite) / soil / building materials
max 2
1 mark
radon gas
1 mark
cosmic rays (from space)
ignore the Sun unless cosmic rays are mentioned
1 mark
food and drink / our own bodies

Question 2

2 marks

Explain why the amount of background radiation from the fallout of nuclear weapons testing is much lower today than it was in the early 1960s.

Model answer

Most countries stopped testing nuclear weapons in the atmosphere, so no new fallout is being added. Much of the radioactive material from the earlier tests has since decayed, so the fallout now gives only a very small dose.

Explanation

Fallout is a man-made source of background radiation. Its contribution depends on how much radioactive material is released and on the half-lives of the isotopes involved.

Mark scheme

1 mark
nuclear weapons tests in the atmosphere have (almost all) stopped / been banned
1 mark
the radioactive isotopes from earlier tests have (mostly) decayed
allow have been dispersed / washed into the ground

Question 3

3 marks

Describe how a student could measure the background count-rate in a laboratory as accurately as possible, using a Geiger-Müller tube and counter.

Model answer

Make sure all radioactive sources are removed from the room. Switch on the Geiger-Müller tube and counter and record the number of counts over a long time, such as 10 minutes, then divide by the time in seconds to find the count-rate. Repeat this several times and calculate the mean count-rate.

Explanation

Background count-rates are low and random, so a short count gives a very unreliable value. Long counting times and repeats make the measured background count-rate much more accurate.

Mark scheme

1 mark
remove all radioactive sources from the room / keep sources well away
1 mark
count for a long time (e.g. 10 minutes) and divide the count by the time
1 mark
repeat several times and calculate a mean

Question 4

4 marks

The legal annual dose limit for a radiation worker is 20 mSv (in addition to background radiation). A worker receives an average of 0.08 mSv on each working day and works 230 days each year. Radiation dose is measured in sieverts (Sv).

Calculate the worker's annual dose from work, in sieverts, and state whether the worker is within the limit.

Model answer

Annual dose = 0.08 × 230 = 18.4 mSv
18.4 mSv = 18.4 ÷ 1000 = 0.0184 Sv
The limit is 20 mSv (0.020 Sv), so the worker is within the limit.

Explanation

Multiply the daily dose by the number of working days, then divide by 1000 to convert millisieverts to sieverts. When comparing with a limit, make sure both values are in the same unit.

Mark scheme

1 mark
0.08 × 230
correct answer with no working scores full marks
1 mark
18.4 mSv
1 mark
0.0184 Sv
allow 1.84 × 10⁻² Sv; allow ecf
1 mark
this is less than 20 mSv / 0.020 Sv, so the worker is within the limit
allow ecf

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