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Interactive practice

Radioactivity & Half-Life Explorer

Compare alpha, beta, gamma, test shielding and deflection, then read half-life data with proper background correction.

  • O Level
  • Explore first
  • 12 min
BetaReviewed Jul 2026Back to O Level Essentials

Focus: Keep measured, background, and net source count-rate separate; shielding reduces what reaches the detector but does not make gamma transmission exactly zero.

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Interactive stageLive model

Study lensCompare alpha, beta, and gamma using charge, ionising power, penetration, and field behaviour together.12 min activity

Try this

Keep measured, background, and net source count-rate separate; shielding reduces what reaches the detector but does not make gamma transmission exactly zero.

Learn to

  • Compare alpha, beta, and gamma using charge, ionising power, penetration, and field behaviour together.
  • Choose suitable shielding, recognise that gamma is attenuated rather than completely stopped, and explain field deflection.
  • Interpret decay graphs and tables, including half-life and background-corrected count rate.

Exam transfer

  • Radiation properties
  • Decay data
  • Half-life

Governing idea

Each undecayed nucleus has the same decay probability per unit time. After each half-life, the expected number remaining, activity, and net count-rate in a fixed detector setup each halve.

Model boundary

Individual decays are random, so small samples fluctuate around the smooth expected curve. Count-rate depends on detector setup, and thick shielding attenuates gamma rather than guaranteeing zero transmission.

Avoid this trap

After two half-lives, one quarter remains—not zero. Subtract background before halving count-rate, and do not describe gamma as completely stopped by one stated shield.

Practice run

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Try Radioactivity Quiz

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Explorer setup

Main mode
16 min
32 min
Data view and background
Options

Radioactivity checkpoint

What to notice:

Prediction target:

      What you'll train

      Learning objectives

      • Compare alpha, beta, and gamma using charge, ionising power, penetration, and field behaviour together.
      • Choose suitable shielding, recognise that gamma is attenuated rather than completely stopped, and explain field deflection.
      • Interpret decay graphs and tables, including half-life and background-corrected count rate.

      Use this when

      • O Level radioactivity revision
      • Students who can list facts but still hesitate with decay data and source-only count rate
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