Chapter 18: Problem 2521
A freshly Prepared radioactive source of half life \(2 \mathrm{~h}\) emits radiation of intensity which is 64 times the Permissible safe level. The minimum time after which is would be possible to work safely with this source is. (A) \(6 \mathrm{~h}\) (B) \(24 \mathrm{~h}\) (C) \(12 \mathrm{~h}\) (D) \(36 \mathrm{~h}\)