A freshly prepared radioactive source of half life 2 hours 30 minutes emits radiation which is 64 ti

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13.Nuclei

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A freshly prepared radioactive source of half life $2$ hours $30$ minutes emits radiation which is $64$ times the permissible safe level. The minimum time, after which it would be possible to work safely with source, will be hours.

A

$14$

B

$18$

C

$15$

D

$75$

(JEE MAIN-2022)

Solution

$A = A _{0} \times 2^{- t / T }$

$\frac{ A _{0}}{64}= A _{0} \times 2^{- t / T }$

$\therefore t =6\,T =6 \times 2.5=15\,hours$

Standard 12

Physics

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