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Formula Radioactive Decay Half-life    Decay constant

Formula
Formula: Radioactive Decay
Radioactive decay law - Graph

Half-life

Unit
Half-life is the period of time after which the initial amount of atomic nuclei has decayed to half.

Decay constant

Unit
Decay constant specifies the probability of decay per unit of time. In other words: The decay constant determines how fast a nuclide (radioactive substance) decays. Different nuclide decay at different rates.

The reciprocal of the decay constant is the lifetime: \( \tau = \frac{1}{\lambda} \).