When stopping potential is applied in an experiment on photoelectric effect, no photo current is observed. This means that

Options

A. the emission of photoelectrons is stopped
B. the photoelectrons are emitted but are re-absorbed by the emitter metal
C. the photoelectrons are accumulated near the collector plate
D. the photoelectrons are dispersed from the sides of the apparatus.

Answer

To solve the question regarding the photoelectric effect and the observation of photocurrent when a stopping potential is applied, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding the Photoelectric Effect**:
- When light of sufficient frequency strikes a metal surface (emitter plate), it can cause the emission of electrons from that surface. This phenomenon is known as the photoelectric effect.

2. **Role of Stopping Potential**:
- In a typical photoelectric experiment, a positive collector plate is placed near the emitter plate. The emitted electrons are attracted to the positive collector plate, creating a photocurrent.
- The stopping potential (V₀) is the negative potential applied to the collector plate to stop the emitted electrons from reaching it.

3. **Effect of Stopping Potential**:
- When a stopping potential is applied, it creates an electric field that opposes the motion of the emitted electrons. If the stopping potential is strong enough, it can completely halt the movement of these electrons towards the collector plate.

4. **Observation of No Photocurrent**:
- If the stopping potential is sufficient to stop all emitted electrons, then no electrons will reach the collector plate. As a result, there will be no flow of current, and thus, no photocurrent will be observed.

5. **Conclusion**:
- The absence of photocurrent indicates that while photoelectrons are emitted from the emitter plate, they are unable to reach the collector plate due to the applied stopping potential. Instead, they are effectively reabsorbed by the emitter plate.

### Final Answer:
When stopping potential is applied in an experiment on the photoelectric effect, no photocurrent is observed because the photoelectrons are emitted but are reabsorbed by the emitter plate.