Question

A freshly prepared radioactive source of half-time 2h emits radiation of intensity which is 64 times the permissible safe level. Minimum time after which it would be possible to work safely with this source is which of the following?

(a) 6 h

(b) 12 h

(c) 24 h

(d) 20 h

I have been asked this question in unit test.

This is a very interesting question from Nucleus topic in section Nucleus of Physics – Class 12

Answer 1

Correct answer is (b) 12 h

Best explanation: \(\frac {N}{N_0} = \frac {1}{64}\).

t = n T1/2

t = 6 × 2hours

t = 12hours.