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Exit to G3 Physics and O-Level Radioactivity Hub

Radioactivity & Half-Life Explorer

Compare radiation types, run shielding and deflection checks, and interpret half-life data with realistic fluctuations and explicit background correction.

  • SEC G3 Physics 2027
Learning goals
  • Explain random and spontaneous nuclear decay
  • Describe alpha, beta-minus and gamma radiation
  • Compare ionising effect and penetrating power
  • Explain background radiation
  • Use half-life in tables and decay curves

Interactive stageLive model

Loading the interactive model…The interactive model did not load. Try again reloads this page; the explanation and worked content here are still available.

Change one variable at a time and watch the model respond.

Explorer setup

Main mode
16 min
32 min
Data view and background
Options

Radioactivity checkpoint

What to notice:

Prediction target:

      Practice run

      Choose a mode and checkpoint count when you want scoring.

      Run mode
      Try Radioactivity Quiz

      Choose your checkpoint count for guided or challenge mode.

      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.

      How to explore

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

      Predict the outcome, change one variable at a time, then interpret the result. Completion records participation only and does not award mastery.

      About this activity

      Compare radiation types, run shielding and deflection checks, and interpret half-life data with realistic fluctuations and explicit background correction. A text explanation and no-JavaScript route remain available.

      How this activity affects progress
      Course and syllabus information
      Course
      SEC G3 Physics
      Edition
      SEC G3 Physics 2027