Radioactive decay
Watch a large population of unstable nuclei dwindle, half-life by half-life.
When an individual nucleus will decay cannot be predicted, but the statistics of a large number of identical nuclei are very stable. After each half-life, the number of undecayed nuclei falls to half, and the activity drops in the same proportion.
Undecayed nuclei vs. time
At each half-life tick, the number of undecayed nuclei is half that at the previous tick.
Think about it
After 3 half-lives, roughly what fraction of the initial nuclei remains undecayed?
About 1/8, that is, 12.5%. Each half-life halves whatever was left after the previous one.
Model assumptionsSingle radioactive nuclide · Constant decay probability · Nuclei decay independently · Nucleus count uses the continuous expected value · Replays automatically after 5 half-lives
Data log
Set the parameters and click “Record data”. Record several rows with different parameters to plot their relationship and fit a straight line; pause and record at different times to study how a reading changes with time.