A slab of materail of dielectric constant `K` has the same area as the plates of a parallel plate capacitor but has thickness `d//2`, where `d` is the separation between the plates. Find the expression for the capacitance when the slab is inserted between the plates.

Explanation

To find the expression for the capacitance of a parallel plate capacitor when a dielectric slab is inserted, we can follow these steps:

### Step-by-Step Solution

1. **Identify the given parameters**:
- Dielectric constant of the slab: \( K \)
- Thickness of the slab: \( \frac{d}{2} \)
- Thickness of the air gap (remaining space): \( \frac{d}{2} \)
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