AQA GCSE Physics contents

Unit 4 · Atomic Structure

Radioactive Decay & Nuclear Radiation

3 min read · part of the full Exam Guide

Radioactive decay

  • Some nuclei are unstable. The nucleus gives out radiation as it changes to become more stable. This is a random process called radioactive decay: you cannot predict when any one nucleus will decay
  • Activity is the rate at which a source of unstable nuclei decays, measured in becquerel, Bq (1 Bq is one decay per second)
  • Count-rate is the number of decays recorded each second by a detector such as a Geiger-Müller tube

Full Exam Guide

The rest of this topic is in the full Exam Guide

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In the full topic

  • Radioactive decay
  • The types of nuclear radiation
  • Nuclear equations
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