Focal lengths of a lens for violet, yellow and red colours are `f_(v), f_(y) and f_(r)` respectively. Calculate the dispersive power of the material of the lens.

Explanation

To calculate the dispersive power of the material of the lens based on the given focal lengths for violet, yellow, and red colors, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Lens Maker's Formula**:
The lens maker's formula relates the focal length of a lens to the refractive index of the lens material and the radii of curvature of its surfaces. The formula is given by:
\[
\frac{1}{F} = (\mu - 1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right)
...