Question

If the refractive index of the crown glass for red, yellow and violet colours are $1.514,1.517\text{and}1.531$ respectively then, the dispersive power of the crown glass will be :

• A. $0.022$
• B. $0.045$
• C. $0.011$
• D. $0.033$

Answer 1

The correct option is D $0.033$

Given,
$n_R=1.514$
$n_Y=1.517$
$n_V=1.531$

We know that,
Dispersive power $\left(\omega \right)=\frac{n_V-n_R}{n_Y-1}$
So, $\omega =\frac{1.531-1.514}{1.517-1}$
$\Rightarrow \omega =\frac{0.017}{0.517}$
$\Rightarrow \omega \approx 0.033$

Hence, option $\left(d\right)$ is the correct answer.