Modern Physics · Physics

Alpha Decay & Half-life Simulation

Watch single nuclei of polonium-211 decay at random, then hundreds at once, and see the random events add up to N = N₀ e^(−λt).

Interactive virtual lab · no download · works on phones and laptops

Chapter: Nuclei
For: Class 12 · JEE · NEET
Time: ~15 min

Alpha Decay & Half-life is a Pro simulation

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How to use it

1Single atom: add a nucleus and record when it decays. Repeat.
2Many atoms: add 1, 10 or 100 nuclei and watch the counts.
3Decay curve: start a batch and compare it with the theory curve.
4Choose a custom half-life to see how λ changes the curve.

What to notice

You cannot predict when one nucleus will decay — only the odds.
Each half-life, about half of whatever remains decays.
More atoms → the measured curve hugs the exponential more closely.
²¹¹₈₄Po → ²⁰⁷₈₂Pb + ⁴₂He: mass number falls by 4, atomic number by 2.

For teachers

A ready-made teaching kit comes with this lab

Lesson plan
22 min, 4 steps
Ask the class
3 questions with answers
Quick quiz
6 questions, printable
Key formulas
4 formulas

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About the Alpha Decay & Half-life simulation

Radioactive decay is random: you cannot tell when a single nucleus will decay, only the chance per second. With many nuclei that chance gives a smooth exponential curve, and the time for half of them to decay — the half-life — is always the same. In alpha decay a nucleus throws out a helium nucleus, losing 2 protons and 2 neutrons.

In this alpha decay simulation you watch a single polonium-211 nucleus wait an unpredictable time before it decays, then add hundreds of nuclei and see the decay curve follow N₀e^(−λt). Change the half-life, record decay times, and compare your measured mean life with T½/ln 2. It covers Nuclei in Class 12, JEE and NEET.

Also covers: radioactivity, half life, polonium, nuclear decay.