Question

The angles of minimum deviations are 53${}^{\circ }$ and 51${}^{\circ }$ for blue and red colors respectively produced in an equilateral glass prism. The dispersive power is :

• A. $\frac{2}{51}$
• B. $\frac{1}{26}$
• C. $\frac{1}{52}$
• D. $\frac{1}{51}$

Answer 1

The correct option is B $\frac{1}{26}$

As ${\delta }_Y=\frac{{\delta }_B+{\delta }_R}{2}$

So ${\delta }_Y=\frac{{53}^{\circ }+{51}^{\circ }}{2}$ =52${}^{\circ }$

$\therefore dispersivepower=\frac{{\delta }_B-{\delta }_R}{{\delta }_Y}$

$=\frac{53-51}{52}$

$=\frac{2}{52}$

$=\frac{1}{26}$