To reduce the capacitance of parallel plate capacitor, the space between the plate is

Options

A. filled with dielectric material
B. reduce and area of the plates is increased
C. increased and area of the plates is decreased
D. increased and area is increased relatively

Explanation

To solve the problem of how to reduce the capacitance of a parallel plate capacitor, we need to analyze the formula for capacitance and the factors that influence it.

### Step-by-Step Solution:

1. **Understand the Formula for Capacitance**:
The capacitance \( C \) of a parallel plate capacitor is given by the formula:
\[ C = \frac{A \epsilon_0}{D} \]
where:
- \( C \) = capacitance
- \( A \) = area of the plates
- \( \epsilon_0 \) = permittivity of free space
- \( D \) = distance between the plates

2. **Identify the Relationship**:
From the formula, we can see that capacitance \( C \) is directly proportional to the area \( A \) and inversely proportional to the distance \( D \) between the plates. This means:
- Increasing \( A \) will increase \( C \).
- Increasing \( D \) will decrease \( C \).

3. **Analyze the Options**:
- **Option A**: Filling the capacitor with a dielectric material increases capacitance (incorrect).
- **Option B**: Reducing the area \( A \) or reducing the distance \( D \) will increase capacitance (incorrect).
- **Option C**: Increasing the distance \( D \) and decreasing the area \( A \) will lead to a decrease in capacitance (correct).
- **Option D**: Increasing both \( D \) and \( A \) at the same rate will keep capacitance the same (also correct, but does not reduce capacitance).

4. **Conclusion**:
To reduce the capacitance of a parallel plate capacitor, you should **increase the distance \( D \) between the plates** and/or **decrease the area \( A \) of the plates**. Thus, the correct answer is **Option C**.