# Calculate the dispersive power for crown glass from given data. $\mu_v= 1.523$ and $\mu_R=1.5145$

$(a)\;0.15 \\ (b)\;0.16 \\ (c)\;0.14 \\ (d)\;0.17$

Here $\mu_v=1.523$
$\mu _R= 1.5145$
Mean refractive index
$\mu =\large\frac{1.523+1.5145}{2}$
$\qquad= 1.51875$
Dispersive Power w is given by
$w= \large\frac{\mu_v-\mu_R}{(\mu-1)}$
$\quad= \large \frac{1.523-1.5145}{(1.51875-1)}$
$\quad =0.1639$
Hence b is the correct answer.