Nuclear Physics Question 4
Question 4 - 29 January - Shift 1
If a radioactive element having half-life of $30 min$ is undergoing beta decay, the fraction of radioactive element remains undecayed after $90 min$. will be :
(1) $\frac{1}{8}$
(2) $\frac{1}{16}$
(3) $\frac{1}{4}$
(4) $\frac{1}{2}$
Show Answer
Answer: (1)
Solution:
Formula: Radioactive Decay
$ \begin{aligned} & \frac{N}{N_0}=(\frac{1}{2})^{t / \frac{1}{2}}=(\frac{1}{2})^{\frac{90}{30}} \\ & \frac{N}{N_0}=(\frac{1}{2})^{3}=\frac{1}{8} \end{aligned} $
