BRAINCAKEDecay Constant
The decay constant λ is the probability that an individual nucleus will decay per unit time. Its unit is s-1, although h-1 or year-1 can be used for long-lived isotopes.
Radioactive decay is random, so it is impossible to predict when a particular nucleus will decay. For a large number N of undecayed nuclei, however, the number decaying per second is proportional to N. The activity is therefore A = λN, measured in becquerels (Bq), where 1 Bq is one decay per second.
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Key terms in this lesson
- half-life
- The average time taken for the number of nuclei of a radioactive isotope in a sample, or its activity, to halve.
More in Radioactivity
- Background Radiation
- Radioactive Decay and Half-life
- Activity
- Radioactive Decay
- Radiocarbon dating
- Argon Dating
- Radioactive Tracers
- Thickness monitoring and Engine Wear
All 25 lessons in Radioactivity · All OCR A-level Physics topics