Radioactive nuclei that are injected into a patient collect at certain sites within its body, undergoing radioactive decay and emitting electromagnetic radiation. These radiations can then be recorded by a detector. This procedure provides an important diagnostic tool called

A radioactive sample has ${N_0}$ active atoms at $t = 0$. 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

At any instant, two elements $X _1$ and $X _2$ have same number of radioactive atoms. If the decay constant of $X _1$ and $X _2$ are $10 \lambda$ and $\lambda$ respectively. then the time when the ratio of their atoms becomes $\frac{1}{e}$ respectively will be

A radioactive sample decays by two modes by $\alpha $ decay and by $\beta -decay$. $66.6 \%$ of times it decays by $\alpha -decay$ and $33.3 \%$ of times, it decays by $\beta -decay$. If half life of sample is $60$ years then what will be half life of sample, if it decays only by $\alpha - decay$. ............ $years$

The half-life of $^{215}At$ is $100\mu s$. The time taken for the radioactivity of a sample of $^{215}At$ to decay to $\frac{{1}}{{16}} \,th$ of its initial value is .........$\mu s$

The graph between the instantaneous concentration $(N)$ of a radioactive element and time $(t)$ is