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Two radioactive materials \mathrm{A}$ and $\mathrm{B} have decay constants 25 \lambda$ and $16 \lambda respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of \mathrm{B} to that of \mathrm{A} will be \mathrm{"e"} after a time  \mathrm{\frac{1}{a \lambda}}. The value of \mathrm{ a} is___________.

Option: 1

9


Option: 2

-


Option: 3

-


Option: 4

-


Answers (1)

best_answer

\mathrm{\lambda_A =25 \lambda }

\mathrm{\lambda_B =16 \lambda }

\mathrm{\frac{N_B}{N_A} =\frac{N_0 e^{-\lambda_B t}}{N_0 e^{-\lambda_A t}}=e }

\mathrm{e^{\left(\lambda_A-\lambda_B\right) t}=e}

\mathrm{but\: \: t=\frac{1}{a \lambda} (\text { Given }) }

\mathrm{\left(\lambda_A-\lambda_B\right) t =1 }

\mathrm{t =\frac{1}{\left(\lambda_A-\lambda_B\right)}=\frac{1}{a \lambda} }

\mathrm{\lambda_A-\lambda_B =a \lambda }

\mathrm{a \lambda =a \lambda }

\mathrm{a =9 }










 

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avinash.dongre

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