Brainlag PlusWhat half-life means, how to read it off a decay graph, and how to work out what is left after a number of half-lives, correcting for background.
Random, but predictable in bulk
One nucleus could decay in the next second or in a thousand years.
But a sample holds billions of nuclei, and in a fixed time a fixed fraction of them decay. So the sample behaves predictably.
The half-life of an isotope is the time for the number of unstable nuclei in a sample to halve, or, the same thing measured, the time for the count rate (or activity) to fall to half. Nothing you do to the sample, heating or squeezing it, changes the half-life.
The rest of this lesson and its 11 practice questions are in Plus.
Screen 1 of 6, free to read.
- 11 exam-style questions, marked as you go, each with a worked solution
- The Radioactive decay simulation</b> and the <b>Half-Life Calculator beside every question
- Anything you get wrong is saved to your flashcards