Question

From the photoelectric effect experiment, following observations are made Identify which of these are correct 
A. The stopping potential depends only on the work function of the metal 
B. The saturation current increases as the intensity of incident light increases 
C. The maximum kinetic energy of a photo electron depends on the intensity of the incident light 
D. Photoelectric effect can be explained using wave theory of light 
Choose the correct answer from the options given below:

• A. A, B, D only
• B. B only
• C. A, C, D only
• D. B, C only

Answer 1

The Correct Option is B

Statement A: The stopping potential depends only on the work function of the metal.

The stopping potential in the photoelectric effect is given by:

Vs = Kmax / e

where Kmax is the maximum kinetic energy of the emitted electrons and e is the elementary charge. According to Einstein's photoelectric equation:

Kmax = hν - φ

where h is Planck's constant, ν is the frequency of the incident light, and φ is the work function of the metal.

Thus, the stopping potential depends on both the frequency of the incident light and the work function of the metal, not solely on the work function.

Statement A is False.

Statement B: The saturation current increases as the intensity of incident light increases.

The saturation current in the photoelectric effect is directly proportional to the number of incident photons, provided that each photon has enough energy to eject an electron. An increase in the intensity of the incident light means more photons are striking the metal surface per unit time, leading to an increase in the number of photoelectrons emitted, and hence, an increase in the saturation current.

Statement B is True.

Statement C: The maximum kinetic energy of a photoelectron depends on the intensity of the incident light.

From Einstein's photoelectric equation:

Kmax = hν - φ

The maximum kinetic energy depends only on the frequency of the incident light and the work function of the metal. It is independent of the intensity of the incident light, which affects the number of photoelectrons but not their kinetic energy.

Statement C is False.

Statement D: Photoelectric effect can be explained using the wave theory of light.

The wave theory of light fails to explain certain observations of the photoelectric effect, such as the existence of a threshold frequency and the instantaneous emission of electrons regardless of light intensity. These phenomena are successfully explained by the particle theory of light, where light consists of photons with quantized energy.

Statement D is False.

Conclusion: Only Statement B is correct.