Question

In a photoelectric effect experiment, a monochromatic light source emitting photons with energy greater than the work function of the metal under test is used. If the power of the light source is doubled, which one of the following statements is correct?

• A. The number of emitted photoelectrons remains the same.
• B. The stopping potential remains the same.
• C. The number of emitted photoelectrons decreases.
• D. The stopping potential doubles.

Hint:

In the photoelectric effect, photon frequency determines electron energy, while intensity determines the number of emitted electrons.

Answer 1

The Correct Option is B

Step 1: Principle of photoelectric effect.
The stopping potential depends only on the energy of the photons (i.e., frequency of light), not on intensity or power.

Step 2: Effect of doubling the light power.
Doubling the power doubles the number of photons hitting the metal surface, thus increasing the number of emitted electrons. However, since photon energy remains constant, the stopping potential does not change.

Step 3: Conclusion.
Hence, when the power of the light source is doubled, the stopping potential remains the same.