If we pull apart the plates of parallel plate capacitor then,

Options

A. The capacitance increases
B. Total charge increases
C. The potential difference increases
D. Capacitance increases

Explanation

To solve the problem regarding the effect of pulling apart the plates of a parallel plate capacitor, we will analyze the situation step by step.

### Step-by-Step Solution:

1. **Understanding Capacitance**: The capacitance \( C \) of a parallel plate capacitor is given by the formula:
\[ C = \frac{\varepsilon_0 A}{d} \]
where \( \varepsilon_0 \) is the permittivity of free space, \( A \) is the area of one of the plates, and \( d \) is the distance between the plates.

2. **Effect of Increasing Distance**: When we pull the plates apart, the distance \( d \) increases. According to the formula, if \( d \) increases, the capacitance \( C \) will decrease because capacitance is inversely proportional to the distance between the plates.

3. **Considering Charge and Voltage**: If the capacitor is connected to a battery, the charge \( Q \) on the capacitor is given by:
\[ Q = C \cdot V \]
where \( V \) is the voltage across the capacitor. If the capacitance \( C \) decreases while the battery is connected, the charge \( Q \) will also decrease because \( V \) remains constant.

4. **Scenario with Disconnected Battery**: If the battery is disconnected before we pull the plates apart, the charge \( Q \) remains constant. In this case, as the capacitance \( C \) decreases (due to increased distance \( d \)), the voltage \( V \) across the capacitor must increase to maintain the relationship:
\[ Q = C \cdot V \]
Since \( Q \) is constant, if \( C \) decreases, \( V \) must increase.

5. **Conclusion**: Therefore, if we pull apart the plates of a parallel plate capacitor, the capacitance decreases, and if the capacitor is disconnected from the battery, the voltage across the capacitor increases.

### Final Answer:
If we pull apart the plates of a parallel plate capacitor, the capacitance decreases, and if the battery is disconnected, the voltage across the capacitor increases.