One face of a rectangular glass plate 6 cm thick is silvered. An object held 8 cm in front of the first face, forms an image 12 cm behind the silvered face. The refractive index of the glass is

Explanation

To solve the problem, we need to find the refractive index of the glass slab given the distances of the object and the image. Let's break down the solution step by step.

### Step 1: Understand the Setup
We have a rectangular glass plate that is 6 cm thick, with one face silvered. An object is placed 8 cm in front of the first face, and an image is formed 12 cm behind the silvered face.

### Step 2: Define Distances
- Let the thickness of the glass slab be \( t = 6 \) cm.
- The object distance \( u = -8 \) cm (the negative sign is used because the object is in front of the mirror).
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