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.

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Vishal Baghel | Contributor-Level 10

6 months ago

t_1/2= 2hr 30 min

Radiation intensity a disintegrations / sec (Activity)

As, $A = \frac{A_{0}}{{2^{t}}^{\frac{t}{2}}}$

For safe working, $A = \frac{A_{0}}{64} \Rightarrow \frac{A_{0}}{64} = \frac{A_{0}}{2^{\frac{t}{t_{\frac{1}{2}}}}}$

$\Rightarrow t = 6 t_{\frac{1}{2}} = 6 * 2.5 h r$

= 15

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Physics Ncert Solutions Class 12th 2023

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