Q. A radioactive material has a half-life of 8 years. The activity of the material will decrease to about 1/8 of its original value in
A) 256 years
B) 128 years
C) 64 years
D) 24 years
Explanation
(d) $\frac{A}{A_{0}} = \left( \frac{1}{2} \right)^{t/T_{1/2}} \Rightarrow \frac{1}{8} = \left( \frac{1}{2} \right)^{t/8} \Rightarrow t = 24\ years$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.