Alpha, beta and gamma: absorbers, range in air and fields sim
Measure the background three times with a GM tube and counter, lift sealed sources out of a lead-lined box with tongs, slide paper, aluminium and lead into the holder one sheet at a time and drag the source back along the track, record your own random counts as count rates and corrected count rates, graph them, identify an unknown source from your readings, and see α, β and γ bend (or not) in electric and magnetic fields.
Radioactivity · covers the O-Level, IGCSE, GCSE topic
What the sim shows
Model: count rate = background (24 cpm, chosen) + each radiation's rate × an inverse-square spread × what gets through. α: stopped by a sheet of paper or about 3.6 cm of air; β: falls as e^(−μx) with μ = 6.6 cm²/g, stopped by about 4.1 mm of aluminium; γ: halved by about 1.0 cm of lead, never stopped. Counts are random (Poisson, seeded). Idealised: one radiation per source, illustrative strengths, no dead time. Step 5 is a model in a vacuum (IGCSE Supplement).
- The source carriage: the part you drag
- Lead-lined source box, tongs, track, absorber holder, GM tube, counter
Use it in your lessons
- Try it here: anyone can unlock 2 figures free, and a free account unlocks up to 5. Runs on a laptop, a Chromebook or a phone; nothing to install.
- Present it and share student links with the teacher plan, from US$5 a month, billed yearly.
- Put it on your own website or LMS for US$9, paid once, or every sim from US$29 a month.
Free guide: 12 practicals as sims, and how to run one in a lesson →
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