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PhysicsModern PhysicsRadioactivityEasy2 minPYQ_2020

PhysicsEasysingle choice

The count rate of a Geiger-Muller counter for the radiation of radioactive material of half life of $30 \min$ decreases to $5 s^{- 1}$ after $2 hr$ . The initial count rate was

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Answer:

Solution:

Given $T_{\frac{1}{2}} = 30 m i n$ ,

$t = 2 h r$

$R = 5 \sec^{- 1}$

$R_{0} = ?$

$n = \frac{t}{T_{\frac{1}{2}}} = \frac{2 \times 80}{30} = 4$

$A . P = \frac{R}{R_{0}} = \frac{1}{2^{n}}$

$R_{0} = 2^{n} R = 2^{4} \times 5$

$∴ R_{0} = 16 \times 5 = 80 s^{- 1}$

Stream:NTA_ABHYAS_NEETSubject:PhysicsTopic:Modern PhysicsSubtopic:Radioactivity

⏱ 2mℹ️ Source: PYQ_2020

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