Dual Nature of Matter

JEE Main level, single correct, medium

117 of 200

Question 117 of 200

Given below are two statements: one is labelled as Assertion A\mathbf{A} and the other is labelled as Reason R.
Assertion A: Number of photons increases with increase in frequency of light.
Reason R: Maximum kinetic energy of emitted electrons increases with the frequency of incident radiation.
In the light of the above statements, choose the most appropriate answer from the options given below:

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Answer: (C) A\mathbf{A} is not correct but R\mathbf{R} is correct.

Intensity of light I=nhνA\mathrm{I}=\frac{\mathrm{nh} \nu}{\mathrm{A}}
Here n\mathrm{n} is no. of photons per unit time.
n=IAhν\mathrm{n}=\frac{\mathrm{IA}}{\mathrm{h} \nu} so on increasing frequency v,nv, \mathrm{n} decreases taking intensity constant.
kmax⁡=hv−ϕ\mathrm{k}_{\max }=\mathrm{h} v-\phi
So on increasing vv, kinetic energy increases.

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