In the photoelectric effect, electromagnetic radiation is incident upon the surface of a metal. Which of the following are true statement about the photoelectric effect?a)The stopping potential is independent of the intensityb)V0 is characteristic of the cathode material.c)Above the threshold frequency, the flux of electrons per second increasesas the intensity of incident light.d)The stopping potential V0is proportional to vCorrect answer is option 'A,B,C'. Can you explain this answer?

Question

Answer

Photoelectric Effect

The photoelectric effect refers to the phenomenon where electrons are emitted from the surface of a material when it is exposed to electromagnetic radiation, typically in the form of light. This effect is important in understanding the behavior of light and the nature of electrons.

True Statements about the Photoelectric Effect

a) The stopping potential is independent of the intensity:
- The stopping potential is the minimum potential difference needed to prevent the emitted electrons from reaching the anode. It is determined by the kinetic energy of the emitted electrons.
- According to the photoelectric effect equation, E = hf - W, where E is the kinetic energy of the emitted electrons, hf is the energy of the incident photons, and W is the work function of the material.
- The stopping potential depends only on the work function of the material and the frequency of the incident light, not its intensity. Increasing the intensity of the light will increase the number of photons incident on the material, but it will not affect the energy of individual photons. Therefore, the stopping potential remains the same regardless of the intensity.

b) V0 is characteristic of the cathode material:
- The stopping potential, V0, is determined by the work function of the material, which is a characteristic property of the cathode material.
- The work function is the minimum amount of energy required to remove an electron from the surface of the material. It depends on the atomic structure and properties of the material.
- Different materials have different work functions, so the stopping potential will vary depending on the cathode material.

c) Above the threshold frequency, the flux of electrons per second increases as the intensity of incident light:
- The threshold frequency is the minimum frequency of light required to cause the photoelectric effect. Below this frequency, no electrons are emitted regardless of the intensity of the light.
- Above the threshold frequency, increasing the intensity of the incident light will increase the number of photons incident on the material, leading to an increase in the number of emitted electrons per unit time. Therefore, the flux of electrons per second increases with increasing intensity.

d) The stopping potential V0 is proportional to v:
- This statement is false. The stopping potential V0 is not proportional to the frequency (v) of the incident light.
- According to the photoelectric effect equation, the stopping potential is determined by the difference between the energy of the incident photons and the work function of the material, not the frequency of the light.

Answer

In the photoelectric effect, by conservation of energy

where

is the work function of the metal. Furthermore,

where

is the work function of the metal. Furthermore,

Thus the stopping potential V₀ is directly proportional to the incident light frequency v²

In fact this is one way of determining Planck’s constant.

Top Courses for Physics

Suggested Free Tests

Related Content

Schools

Competitive Examinations

Quick Access Links

Technical Exams