A photon of energy 7 eV is incident on a metal surface having the work function of 3.75 eV. What is the stopping potential ?

Options

A. 2 V
B. 3 V
C. 3.25 V
D. 4.5 V

Explanation

To solve the problem, we need to determine the stopping potential (\(V_s\)) for a photon incident on a metal surface. The stopping potential can be calculated using the energy of the photon and the work function of the metal.

### Step-by-Step Solution:

1. **Identify Given Values:**
- Energy of the photon (\(E_{\text{photon}}\)) = 7 eV
- Work function of the metal (\(W_0\)) = 3.75 eV

2. **Understand the Concept of Stopping Potential:**
- The stopping potential is the potential difference needed to stop the emitted photoelectrons from reaching the anode. It can be calculated using the equation:
\[ eV_s = E_{\text{photon}} - W_0 \]
where \(e\) is the charge of the electron (which cancels out in the equation since we are working in electron volts).

3. **Substitute the Given Values into the Equation:**
\[ V_s = E_{\text{photon}} - W_0 \]
\[ V_s = 7 \, \text{eV} - 3.75 \, \text{eV} \]

4. **Perform the Calculation:**
\[ V_s = 3.25 \, \text{eV} \]

5. **Conclusion:**
- The stopping potential (\(V_s\)) is 3.25 V.

### Final Answer:
The stopping potential is **3.25 V**.

---