Question

A freshly prepared radioactive substance of half life 2 hour emits radiations of density 64 times the permissible safe level. The minimum time after which it would be possible to work safely with this substance is

Answer 1

Explanation:

The minimum time after which it would be possible to work safely with this substance is when he level of radiation is minimum

So taking N' /N = 1 /64

Where N' is min density and N is initial density

N' /N = (1/2) ^ t/ t₁/₂

1/64 = (1/2)⁶ = (1/2) ^ t/ t₁/₂

6 = t / 2  ------- > t = 12 hours