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 freshly prepared radioactive sample of half- life $1$ hour emits radiations that are $128$ times as intense as the permissible safe limit. The minimum time after which this sample can be safely used is .........$hours$
The half life of a radioactive isotope $X$ is $50$ years. It decays to another element $Y$ which is stable. The two elements $X$ and $Y$ were found to be in the ratio of $1 : 15$ in a sample of a given rock. The age of the rock was estimated to be..........$years$
In a radioactive sample there are $1.414 \times 10^6$ active nuclei. If they reduce to $10^6$ within $10\, minute$ then the half life of this sample will be ....... $min$
The nuclide $^{131}I$ is radioactive, with a half-life of $8.04$ days. At noon on January $1$, the activity of a certain sample is $60089$. The activity at noon on January $24$ will be
Radioactive substances do not emit