Explain what is meant by the term 'nuclear radiation' and describe TWO properties that distinguish beta radiation from gamma radiation.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Unstable nuclei can emit different types of nuclear radiation. Scientists use the properties of these radiations to identify them and to determine how dangerous they are.
Model answer (4 marks)
Nuclear radiation is ionising radiation that is emitted spontaneously from an unstable nucleus.
Beta radiation:
1. It is a fast‑moving electron (or positron) emitted from the nucleus, so it has mass and charge.
2. It has a short to moderate penetrating power – a few millimetres of aluminium can stop it.
Gamma radiation:
1. It is an electromagnetic photon, with no mass or charge.
2. It has a much greater penetrating power – several centimetres of lead or metres of concrete are required to absorb it.
Beta radiation:
1. It is a fast‑moving electron (or positron) emitted from the nucleus, so it has mass and charge.
2. It has a short to moderate penetrating power – a few millimetres of aluminium can stop it.
Gamma radiation:
1. It is an electromagnetic photon, with no mass or charge.
2. It has a much greater penetrating power – several centimetres of lead or metres of concrete are required to absorb it.
Examiner tips
- Define nuclear radiation first, then give two clear, contrasting properties of beta and gamma.
- Use the exact terms ‘electron’, ‘photon’, ‘penetrating power’ and mention the shielding materials as the mark scheme expects.
- Keep the answer concise – 4 marks only, no extra explanation.
Mark scheme (4 marks)
- Nuclear radiation is (ionising) radiation emitted from an unstable nucleus (spontaneously / randomly)
- Beta radiation has a short/moderate penetrating power (stopped by a few mm of aluminium) whereas gamma radiation has much greater penetrating power (requires several cm of lead or metres of concrete to absorb it)
- Beta radiation is a fast-moving electron (emitted from the nucleus) whereas gamma radiation is an electromagnetic wave / photon (with no mass and no charge)
- Beta radiation causes more ionisation than gamma radiation (per unit path length) / gamma radiation is less ionising than beta radiation
Key terms in this question
nuclear radiation · beta radiation · gamma radiation
Related
- All WJEC GCSE Physics (Wales) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More The atom, the nucleus and radioactivity questions
- A radioactive source emits beta particles. Explain what a beta particle is and d…
- A student states that all atoms contain three types of subatomic particle. State…
- Gamma radiation, alpha particles and beta particles are all types of nuclear rad…
- Describe what is meant by alpha decay and explain why the nucleus of an atom und…