Question

If the refractive indices of a prism for red, yellow and violet colours be 1.61, 1.63 and 1.65 respectively, then the dispersive power of the prism will be:

• A. $\frac{1.65-1.62}{1.61-1}$
• B. $\frac{1.62-1.61}{1.65-1}$
• C. $\frac{1.65-1.61}{1.63-1}$
• D. $\frac{1.65-1.63}{1.61-1}$

Answer 1

The correct option is C $\frac{1.65-1.61}{1.63-1}$

Dispersive power of the prism=$\frac{{\mu }_v-{\mu }_r}{{\mu }_y-1}=\frac{1.65-1.61}{1.63-1}$