The plane surface of a plano-convex lens of refracting index 1.5, is silvered. The radius of curvature of curved surface is R. Find the focal length of the mirror thus formed.

Explanation

To find the focal length of the mirror formed by silvering the plane surface of a plano-convex lens, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the System**: We have a plano-convex lens with a refractive index (μ) of 1.5 and a radius of curvature (R) for the curved surface. The plane surface is silvered, effectively turning the lens into a mirror system.

2. **Understand the Focal Length of the Lens**: For a plano-convex lens, the formula for the focal length (f) is given by:
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