Two radioactive substances $A$ and $B$ have decay constants $5\lambda $ and $\lambda $ respectively. At $t = 0$, a sample has the same number of the two nuclei. The time taken for the ratio of the number of nuclei to become $(\frac {1}{e})^2$ will be
Two radioactive substances $A$ and $B$ have decay constants $5\lambda $ and $\lambda $ respectively. At $t = 0$, a sample has the same number of the two nuclei. The time taken for the ratio of the number of nuclei to become $(\frac {1}{e})^2$ will be
- [JEE MAIN 2019]
- A
$1/\lambda $
- B
$1/4\lambda $
- C
$2/\lambda $
- D
$1/2\lambda $
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- [IIT 2001]
The activity $R$ of an unknown radioactive nuclide is measured at hourly intervals. The results found are tabulated as follows:
$t(h)$
$0$
$1$
$2$
$3$
$4$
$R(MBq)$
$100$
$35.36$
$12.51$
$4.42$
$1.56$
$(i)$ Plot the graph of $R$ versus $t$ and calculate half-life from the graph.
$(ii)$ Plot the graph of $\ln \left( {\frac{R}{{{R_0}}}} \right) \to t$ versus $t$ and obtain the value of half-life from the graph.
The activity $R$ of an unknown radioactive nuclide is measured at hourly intervals. The results found are tabulated as follows:
| $t(h)$ | $0$ | $1$ | $2$ | $3$ | $4$ |
| $R(MBq)$ | $100$ | $35.36$ | $12.51$ | $4.42$ | $1.56$ |
$(i)$ Plot the graph of $R$ versus $t$ and calculate half-life from the graph.
$(ii)$ Plot the graph of $\ln \left( {\frac{R}{{{R_0}}}} \right) \to t$ versus $t$ and obtain the value of half-life from the graph.