Physics · GCSE · Atoms & Radioactivity
Half-life
gcse-phys-6-4-2-3Free3:51Heddy Score 2 of 7, below the standardPlays from youtube-nocookie.com. No YouTube cookies until you press play.
What you need to know
- Half-life is the time for half the unstable nuclei in a sample to decay.
- It is also the time for the count-rate from a sample to halve.
- Half-life can be read from a graph of count-rate against time.
- After each half-life the remaining activity halves again, so it can be calculated after several half-lives.
In this clip
0:31–4:22Half-lifegcse-phys-6-4-2-3Heddy ScoreSeven checks every clip must pass before students see it: trusted, on the map, accurate, focused, accessible, safe, and proven by students.2/7, Below the standard
- Trusted source · passed. The creator's own upload, live and playable here.
- On the map · not judged yet. A teacher watched it: it mainly teaches this map topic.
- Spec-true · not judged yet. Accurate, and right for the current UK specification.
- Focused · passed. One idea, short enough to watch in one go.
- Accessible · not judged yet. Good captions, clear sound and pictures.
- Safe for children · not judged yet. Right for 11 to 16 year olds, with no sales pitch.
- Proven · not judged yet. Earned from our students: they learn from it, find it helpful and watch it to the end.
Our students
How the Heddy Score worksNot enough students yet
Our own students' answers. These are what move ★7 Proven.Why we picked it
Freesciencelessons lesson on half-life, reading it from a graph and calculating count-rates; GCSE.
Freesciencelessons on YouTubechecked 2026-10-16