What is the formula for half-life period?

Half-life period is used in nuclear physics to describe how quickly unstable atoms undergo, or how long stable atoms survive a radioactive decay. It is the time required for a quantity to reduce to half its initial value.

we know N = N₀ e^-λt and half life T = t  , N = N₀ / 2

substituting these values we get,

N₀/ 2 = N₀ e^-λt

1/ 2 = e^-λt

e^λt = 2

λ T = log _e 2

λ T = 0.693 —– value of log _e 2 is 0.693

T = 0.693 /λ

Where

T = half-life period

λ =the decay constant of the decaying quantity.