Q. A radioactive sample has $N_{0}$ active atoms $t = 0$. If the rate of disintegration at any time is $R$ and the number of atoms is $N$, then the ratio $R/N$ varies with time as
A)
B)
C)
D)
Explanation
(d) Rate $R = - \frac{dN}{dt} = \lambda N_{0}e^{- \lambda t} = \lambda N \Rightarrow \frac{R}{N} = \lambda$ (constant) $i.e.,$ graph between $\frac{R}{N}$ and $t$, is a straight line parallel to the time axis
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.