Question

Find the correct statement(s) about photoelectric effect.
A. There is no significant time delay between the absorption of a suitable radiation and the emission of electrons.
B. Einstein analysis gives a threshold frequency above which no electrons can be emitted.
C. The maximum kinetic energy of the emitted photoelectrons is proportional to the frequency of incident radiation.
D. The maximum kinetic energy of electrons does not depend on the intensity of radiation.

Answer 1

The photoelectric emission is an instantaneous process. The photoelectric emission occurs above a cut-off frequency and the kinetic energy and the frequency are in a linear relation.

Complete step by step answer:
The phenomenon of emission of electrons from metal surfaces exposed to light energy of suitable frequency is known as photoelectric effect.
There exists a certain minimum cut-off frequency, called the threshold frequency of the incident radiation below which no emission takes place for a given photosensitive material, irrespective of the intensity of the incident radiation.
The maximum kinetic energy increases linearly with the frequency of the incident radiation. The maximum kinetic energy of photoelectrons and frequency of incident radiation are independent of intensity of radiation.
The photoelectric emission is an instantaneous process. The time lag is very small, insignificant, between the incidence of radiation and emission of photoelectrons. If frequency of the incident radiation exceeds the threshold frequency, the photoelectric emission starts without any apparent time lag even if the incident radiation is very dim.

So, the correct answers are “Options A,C and D”.

Note:
The threshold frequency depends on the photosensitive material and not on the source of incident light. The threshold frequency is different for different metals. No, photoelectric emission is possible for a frequency of incident radiation, lower than the cut-off frequency, even if the intensity is large.
The maximum kinetic energy depends on the frequency of light source and the emitter plate material.