What is meant by dispersive power ? Write an expression of dispersive power in terms of refractive indices.

Explanation

### Step-by-Step Solution:

1. **Understanding Dispersion**:
Dispersion occurs when white light passes through a prism and separates into its component colors. This happens because different colors (wavelengths) of light refract at different angles when they enter and exit the prism.

2. **Identifying Colors**:
In a triangular prism, the colors separate with red light at the top and violet light at the bottom. This indicates that violet light is deviated more than red light.

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