Question

Given below are two statements : one is labelled as Assertion 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 : 

(1) Both A and R are correct and R is NOT the correct explanation of A. 

(2) A is correct but R is not correct. 

(3) Both A and R are correct and R is the correct explanation of A. 

(4) A is not correct but R is correct

Answer 1

Correct option is : (4) A is not correct but R is correct.

Intensity of light \(\ \mathrm{I}=\frac{\mathrm{nh} \nu}{\mathrm{A}}\)

Here \(\mathrm{n}\) is no. of photons per unit time.

\(\mathrm{n}=\frac{\mathrm{IA}}{\mathrm{h} \nu}\) so on increasing frequency \(v, \mathrm{n}\) decreases taking intensity constant.

\(\mathrm{k}_{\max }=\mathrm{h} \nu-\phi\)

So on increasing v, kinetic energy increases.