Question

In a photoelectric experiment, if both the intensity and frequency of the incident light are doubled then the saturation photo electric current

• A. is doubled
• B. remains constant
• C. becomes four times
• D. is halved

Answer 1

The Correct Option is A

According to the photoelectric effect, the number of electrons emitted by a material depends on the intensity of the incident light, while the kinetic energy of the emitted electrons depends on the frequency of the incident light. 
If both the intensity and frequency of the incident light are doubled, the following changes occur: 
Doubling the intensity of the light: Increasing the intensity of light means more photons are incident on the material, leading to a higher number of electrons being emitted. Therefore, the saturation photocurrent will be doubled. 
Doubling the frequency of the light: Increasing the frequency of light implies that each photon carries more energy. Consequently, the emitted electrons will have higher kinetic energy. However, doubling the frequency alone doesn't directly affect the saturation photocurrent. 
In summary, doubling both the intensity and frequency of the incident light will result in the saturation photocurrent being doubled. 
Therefore, the correct option is (A) the saturation photocurrent is doubled.

Answer 2

According to the photoelectric effect:

• The saturation photoelectric current is directly proportional to the intensity of the incident radiation.
• The saturation photoelectric current is independent of the frequency of the incident radiation.

The saturation photoelectric current $I_{\text{sat}}$ is given by the relation:

$I_{\text{sat}} \propto \text{Intensity}$

When both intensity and frequency are doubled:

• The frequency of the incident radiation does not affect the saturation photoelectric current because the current depends only on the number of emitted electrons, which is influenced by intensity.
• The intensity of the radiation is directly proportional to the number of photons striking the surface, and thus, it directly affects the number of electrons emitted and the current.

If the intensity is doubled, the saturation photoelectric current also doubles. Since the frequency does not affect the current, doubling the frequency has no effect.

Conclusion:

When both the intensity and frequency are doubled, the saturation photoelectric current becomes doubled because the frequency does not influence the current.

Therefore, the saturation photoelectric current will be:

$I_{\text{sat}} \propto 2 \times \text{Intensity}$