Double convex lenses are to be manufactured from a glass of refractive index 1.55, with both faces of the same radius of curvature. What is the radius of curvature required if the focal length of the lens is to be 20 cm?

Explanation

To find the radius of curvature required for a double convex lens made from glass with a refractive index of 1.55, given that the focal length of the lens is 20 cm, we can use the lens maker's formula. The steps are as follows:

### Step-by-Step Solution:

1. **Understand the Lens Maker's Formula**:
The lens maker's formula is given by:
\[
\frac{1}{f} = (\mu - 1) \left( \frac{1}{r_1} - \frac{1}{r_2} \right)
...