Question

If intensity of incident light is increased in PEE (Photoelectric effect experiment) then which of the following is true
A. Maximum K.E of the ejected electron will increase
B. Work function will remain unchanged
C. Stopping potential will decrease
D. Maximum K.E of the ejected electron will decrease

Answer 1

Hint: In order to answer this question, we have to use the results of the photoelectric effect experiment. In this experiment, when we incident the light of a certain frequency which is greater than the threshold frequency then the photoelectrons are emitted.

Complete step by step solution:
If the intensity of the incident light is increased then the photoelectric current increases because the number of photons increases in incident light. If the total number of incident photons increases, then the number of emitted photoelectrons also increases, as a result, the photoelectric current increases.

The greater the intensity of incident radiation, the larger the number of incident photons and hence larger the number of electrons ejected from the metal surface. Therefore, if the incident radiation’s intensity will increase then the total number of electrons throughout will also increase.

With the increase in the intensity of light photoelectric current increases, but the kinetic energy of the ejected electron, stopping potential as well as work function remains unchanged. For different materials, the work function will also be different and the kinetic energy of ejected electrons depends on the energy of the incident radiation and is independent of the intensity of incident radiation.

Hence option B is the correct answer.

Note: The work function is defined as the minimum amount of energy required to induce photoemission of electrons from a metal surface. Since the emission of photoelectrons is directly proportional to the intensity of the incident light, the photocurrent increases with the intensity of light. The light intensity relates to the number of photons incident on the metal surface per unit of time. At low light intensity, the photoelectric effect still occurs.