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

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

Tardigrade Admin · Accepted Answer

The dispersive power for crown glass ω=(nv-nr/ny-1) =(1.5318-1.5140/(1.5170-1))=(0.0178/0.5170)=0.034 and for flint glass ω'=(1.6852-1.6434/(1.6499-1))=0.064

Q. 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

0.034 and 0.064

0.064 and 0.034

1.00 and 0.064

0.034 and 1.0

The dispersive power for crown glass $ω = \frac{n _{v} - n _{r}}{n _{y} - 1}$
$= \frac{1.5318 - 1.5140}{( 1.5170 - 1 )} = \frac{0.0178}{0.5170} = 0.034$
and for flint glass $ω^{'} = \frac{1.6852 - 1.6434}{( 1.6499 - 1 )} = 0.064$

Q. 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