Radioactive Activity (A = λN)

A=λNA = \lambda N

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Each nucleus decays with fixed probability λ per second, so a sample's total click rate is simply λN — measured in becquerels (1 Bq = 1 decay/s) or the older curie (3.7 × 10¹⁰ Bq, the activity of a gram of radium). The relation runs both ways: count the clicks and you have counted the atoms. Carbon dating works exactly so — a gram of living carbon clicks about 0.23 times per second, and every halving of that rate marks 5,730 years since death.

Radioactive Activity (A = λN)
A=λNA = \lambda N
Where
  • AA= Activity
  • λ\lambda= Decay constant
  • NN= Number of nuclei
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