Question 3 of 239
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Emission of electrons in photoelectric effect can be suppressed by applying a sufficiently negative electron potential to the photoemissive substance.
Reason (R) : A negative electric potential, which stops the emission of electrons from the surface of a photoemissive substance, varies linearly with 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: (D) Both \((\mathbf{A})\) and \((\mathbf{R})\) are true but \((\mathbf{R})\) is not the correct explanation of \((\mathbf{A})\)
Assertion (A) is true because a sufficiently negative potential can repel and stop the emitted electrons from leaving the surface.
Reason (R) is also true because the stopping potential \(V_{\text {stop }}\) varies linearly with the frequency \(\nu\) of the incident light \(\left(V_{\text {stop }}=\frac{h}{e} \nu-\frac{\phi}{e}\right)\).
However, (R) does not directly explain why a negative potential suppresses electron emission; it only shows how much potential is needed for different frequencies.
Therefore, both (A) and (R) are true, but (R) is not the correct explanation of (A).
Reason (R) is also true because the stopping potential \(V_{\text {stop }}\) varies linearly with the frequency \(\nu\) of the incident light \(\left(V_{\text {stop }}=\frac{h}{e} \nu-\frac{\phi}{e}\right)\).
However, (R) does not directly explain why a negative potential suppresses electron emission; it only shows how much potential is needed for different frequencies.
Therefore, both (A) and (R) are true, but (R) is not the correct explanation of (A).