Question

The time taken by a photoelectron to come out after the photon strikes is approximately.
(A) ${10}^{-1}s$
(B) ${10}^{-2}s$
(C) ${10}^{-10}s$
(D) ${10}^{-16}s$

Answer 1

Hint To find the correct option, you first of all need to know that even though the kinetic energy does depend upon the energy of the incident light beam, but the time taken by a photoelectron to come out after the photon of the incident light beam strikes is not dependent

Complete step by step answer
As it is apparent from the given options as well as explained in the hint section of the solution to the asked question, the time taken by a photoelectron to come out after the photon strikes is almost constant no matter what incident light rays of any intensity you use. Even though the maximum kinetic energy achieved by the photoelectrons will differ as the intensity and frequency of the incident light rays vary, the time by the photoelectron to come out would not vary since it is independent of the intensity and frequency of the incident light beams. The only necessary condition for photoelectrons to come out is that the frequency of the incident light rays is higher than the threshold frequency of the material of the plate being used. Note that this also gives us an insight that the time taken by the photoelectrons to come out does not depend on the material of the plate being used either and is independent of literally every factor that could have affected it.
As we can see it being cited in many study material and published articles and science pages, the time taken by a photoelectron to come out after the photon strikes is almost constant and is equal to ${10}^{-10}s$ approximately. This has been witnessed in multiple experiments and has been proven to be a fact and a stepping stone in the study of photoelectric effect, giving us a major stand on the fact that light rays and the material of the plate cannot change the time taken by the photoelectron to come out once the sufficient energy is given to it by the incident photons of the incident light rays.

Hence, the correct option is option (C).

Note The only major confusion would have been if there was another option saying that the time depends on the intensity of the incident light rays as many students will believe that more energized light ray will cause the electrons to come out faster. Which is a wrong notion as more energized light rays or photons only affect the maximum kinetic energy but not the time taken to come out.