Modern Physics 3 Question 22

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

(1988, 2M)

(a) 6h

(b) 12h

(c) 24h

(d) 128h

Show Answer

Solution:

  1. From R=R012n

we have, 1=6412n

or n=6= number of half lives

t=n×tt1/2=6×2=12h



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