Q153 / 200 · Manipal (MET) 2010 · Physics

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

  • Correct answer
    A
    12 h
  • B
    24 h
  • C
    6 h
  • D
    130 h

Solution

For working safely, the activity must reduce to $\frac{1}{64} .$ $\frac{N}{N_0}=\left(\frac{1}{2}\right)^n=\frac{1}{64}$ $\therefore n=6$ Thus, $t=n T=6 \times 2=12 \mathrm{~h}$

Hence, the correct answer is option: 'A'.

Relevant Questions