Question

If the refractive indices of crown glass for red, yellow and violet colours are 1.5140, 1.5170 and 1.5318 respectively and for flint glass these are 1.6434, 1.6499 and 1.6852 respectively, then the dispersive powers
for crown and flint glass are respectively

• A. 0.034 and 0.064
• B. 0.064 and 0.034
• C. 1.00 and 0.064
• D. 0.034 and 1.0

Answer 1

The correct option is A 0.034 and 0.064

${\omega }_{Crown}=\frac{{\mu }_v-{\mu }_r}{{\mu }_y-1}=\frac{1.5318-1.5140}{(1.5170-1)}=0.034;{\omega }_{Flint}=\frac{{\mu }_v^{\prime }-{\mu }_r^{\prime }}{{\mu }_y-1}=\frac{1.6852-13634}{1.6499-1}=0.064$