BRAINCAKEArgon Dating
Potassium-40 in rocks undergoes electron capture and changes to argon-40 and a neutrino. The argon-40 is trapped in the rocks. Potassium-40 also decays by beta emission to form Calcium-40. The probability of potassium decaying to calcium is 8x greater than the probability of electron capture so the half-life of electron capture is effectively 1250 million years. The age of the rock can then be calculated by measuring the proportion of argon-40 to potassium-40 in the rock.
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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
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- Radioactive Decay
- Decay Constant
- Radiocarbon dating
- Radioactive Tracers
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- Power Sources
- N-Z Graph
All 25 lessons in Radioactivity · All OCR A-level Physics topics