Law of radioactive decay

N=N_0\left(\tfrac12\right)^{t/T_{1/2}}

Result unit: — (number of nuclei)

What it describes

The number of undecayed nuclei decreases exponentially — after each half-life, half remains.

N

number of nuclei after time

t

N_0

initial number of nuclei

t

time

[s]

T_{1/2}

half-life

[s]

Decay is random, but statistically after each half-life half of the nuclei remain. After 2 periods — ¼, after 3 — ⅛.

Dating (e.g. with carbon C-14), activity of radioactive samples.

After how many half-lives will ⅛ of the initial number of nuclei remain?

Substitution

(\tfrac12)^n=\tfrac18

Result

n=3

half-lives.

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