(b) Obtain the expression for the capacitance of a parallel plate capacitor.

Explanation

To derive the expression for the capacitance of a parallel plate capacitor, we can follow these steps:

### Step 1: Understand the Electric Field Between the Plates
The electric field \( E \) between two infinitely large parallel plates with surface charge densities \( +\sigma \) and \( -\sigma \) is given by:
\[ E = \frac{\sigma}{\epsilon_0} \]
where \( \epsilon_0 \) is the permittivity of free space.
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