Question

In photoelectric emission, the value of the saturation current depends on:

• A. the frequency of incident light.
• B. the work function of the surface.
• C. the intensity of incident light.
• D. the anode potential.

Hint:

Saturation current counts electrons emitted per second, and each photon frees one electron, so think about what controls the photon count.

Answer 1

The Correct Option is C

Step 1: Understand saturation current.
In a photoelectric experiment, when the anode potential is made large enough (positive), every emitted photoelectron reaches the anode. The current then stops increasing and levels off at a maximum value called the saturation current.

Step 2: What fixes the number of photoelectrons.
The saturation current is proportional to the number of photoelectrons emitted per second. Each photon can eject at most one electron, so the number of electrons emitted per second is proportional to the number of photons striking the surface per second, i.e. the intensity of the incident light.

Step 3: Rule out the other choices.
Frequency (i) and work function (ii) control the maximum kinetic energy / stopping potential of the electrons, not how many are emitted. Anode potential (iv) only decides whether we have reached saturation; beyond the saturating value, raising it further does not increase the current.

Step 4: Conclusion.
Saturation current \( \propto \) intensity of incident light, so option (iii) is correct.

\[\boxed{I_{sat}\ \propto\ \text{intensity}}\]