Radioactive substances emit different types of nuclear radiation. Describe the nature of alpha radiation and beta radiation, including the composition of each type and how each is affected when passed through a magnetic field.

Eduqas GCSE Physics — 2.4 The atom, the nucleus and radioactivity · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Alpha radiation is a helium nucleus, consisting of two protons and two neutrons. It is positively charged and is deflected to the left in a magnetic field.
Beta radiation is a fast‑moving electron emitted from the nucleus. It carries a negative charge and is deflected to the right in a magnetic field.

Examiner tips

  • Use the exact composition of alpha (2p+2n) and beta (electron).
  • State the charge and direction of deflection in a magnetic field.
  • Show the opposite directions for alpha and beta.

Common mistakes

  • Confusing alpha with a proton or neutron only.
  • Forgetting that beta is an electron and negative.

Mark scheme (4 marks)

  1. Alpha radiation consists of two protons and two neutrons (a helium nucleus).
  2. Beta radiation consists of a fast-moving electron emitted from the nucleus.
  3. Alpha radiation is deflected in a magnetic field (in the opposite direction to beta).
  4. Beta radiation is deflected in the opposite direction to alpha in a magnetic field (because it carries a negative charge).

Key terms in this question

alpha radiation · beta radiation · magnetic field

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