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 the photoelectric effect can be suppressed by applying a sufficiently negative electric 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 the frequency of incident radiation.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer: (D) Both (A) and (R) are true but (R) is not the correct explanation of (A)
**(A)** A large enough retarding (stopping) potential turns back even the fastest photoelectrons, so the photocurrent stops. True.
**(R)** From $eV_0 = h\nu - \phi$, the stopping potential varies linearly with frequency. True.
(R) describes how the stopping potential depends on frequency; it is not the reason emission can be suppressed, so it does not explain (A).
Solution by Sreeraj P, M.Sc Physics