In photoelectric effect, the work function of a metal is 3.7 eV. The emitted electron can be stopped by applying a potential of 1.8 V. Then

Options

A. the energy of the incident photon is 1.9 eV
B. the energy of the incident photon is 5.5 eV
C. if the energy of the incident photon is 3 eV, then the electron will be emitted with maximum energy
D. the energy of the incident photon is 11 eV

Explanation

To solve the problem regarding the photoelectric effect, we need to follow these steps:

### Step 1: Understand the Given Values
We are given:
- Work function of the metal, \( W = 3.7 \, \text{eV} \)
- Stopping potential, \( V_s = 1.8 \, \text{V} \)

### Step 2: Relate Stopping Potential to Energy
The stopping potential is the potential required to stop the emitted electrons. The energy of the emitted electrons can be expressed in terms of the stopping potential:
\[ E = e V_s \]
where \( e \) is the charge of an electron (approximately \( 1 \, \text{eV/V} \)). Therefore, the energy associated with the stopping potential is:
\[ E = 1.8 \, \text{eV} \]

### Step 3: Calculate the Energy of the Incident Photon
According to the photoelectric effect, the energy of the incident photon \( E_{\text{photon}} \) can be calculated using the work function and the stopping potential:
\[ E_{\text{photon}} = W + E \]
Substituting the known values:
\[ E_{\text{photon}} = 3.7 \, \text{eV} + 1.8 \, \text{eV} \]

### Step 4: Perform the Calculation
Now, we perform the addition:
\[ E_{\text{photon}} = 5.5 \, \text{eV} \]

### Conclusion
The energy of the incident photon is \( 5.5 \, \text{eV} \).

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