Question

Two different radioactive elements with half lives `T_1 and T_2` have `N_1 and N_2` (undecayed) atoms respectively present at a given instant. Determine the ratio of their activities at this instant.

Answer 1

We know `A=(dN)/(dt)=lambdaN=(0.693N)/T`
`:. A_1=(0.693N_1)/(T_1) and A_2=(0.693N_2)/(T_2) `
`(A_1)/(A_2)=(N_1)/(T_1)xx(T_2)/(N_2)=((N_1)/(N_2))((T_2)/(T_1))`