Question

State the law of radioactive decay. Write the SI unit of 'activity'.

Answer 1

The law of radioactive decay: When a radioactive material undergoes a decay, the number of nuclei undergoing the decay, per unit time is proportional to the total number of nuclei in the sample material.

$\frac{dN}{dt}\propto N$

$\frac{dN}{dt}=\lambda N$

or

$N=N_0{e}^{-\lambda t}$

SI unit of 'activity' is Becquerel (Bq)

$1Bq=1decaypersecond$