A certain radioactive material can undergo three different types of decay, each with a different decay constant $\lambda_1$, $\lambda_2$ and $\lambda_3$ . Then the effective decay constant is
$\lambda_{eff} =\frac{\lambda_1+\lambda_2+\lambda_3}{3}$
$\frac{1}{\lambda_{eff}}=\frac{1}{\lambda_{1}}+\frac{1}{\lambda_{2}}+\frac{1}{\lambda_{3}}$
$\lambda_{eff} =\lambda_1+\lambda_2+\lambda_3$
$\frac{1}{\lambda_{eff}}=\frac{1}{3}(\frac{1}{\lambda_{1}}+\frac{1}{\lambda_{2}}+\frac{1}{\lambda_{3})}$
A radioactive sample consists of two distinct species having equal number of atoms $N_0$ initially. The mean-life of one species is $\tau $ and of the other is $5\tau $. The decay products in both cases is stable. The total number of radioactive nuclei at $t = 5\tau $ is
A radioactive nucleus is being produced at a constant rate $\alpha$ per second. Its decay constant is $\lambda $. If $N_0$ are the number of nuclei at time $t = 0$, then maximum number of nuclei possible are
Carbon $ - 14$ decays with half-life of about $5,800\, years$. In a sample of bone, the ratio of carbon $ - 14$ to carbon $ - 12$ is found to be $\frac{1}{4}$ of what it is in free air. This bone may belong to a period about $x$ centuries ago, where $x$ is nearest to
Who invented radioactivity ?
Define $SI$ unit of radioactivity ?