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NEET 2010 (AIPMT, Prelims) · Law of Radioactive Decay

Law of Radioactive Decay question from NEET 2010 (AIPMT, Prelims)

Q105NEET 2010 · AIPMT · PRELIMSMedium

Law of Radioactive Decay

The activity of a radioactive sample is measured as N0 counts per minute at t = 0 and N0/e counts per minute at t = 5 minutes. The time (in minutes) at which the activity reduces to half its value is

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Answer: (d)

$\frac{N_0}{e} = N_0e^{-5\lambda} \Rightarrow \lambda = \frac{1}{5}\text{ min}^{-1}$ .
$T = \frac{\log_e2}{\lambda} = 5\log_e2$ min.
So the answer is (d) $5\log_e2$ .

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