Question

angles of deviation for extreme colours
are given for different prisms. Select the
one having maximum dispersive power
of its material.
(A) 7°, 10° (B) 8°, 11°
(C) 12°, 16° (D) 10°, 14°​

Answer 1

Answer:

Option (a) 7°, 10°

Step-by-step explanation:

Dispersive power of a medium is given by

$\boxed{\omega=\frac{\delta_F-\delta_C}{\delta_D}}$

where, $\delta_F$ and  $\delta_C$ are the angles of deviation for the blue and red colours respectively. Also called the difference in the angles of deviation of extreme colours.

$\delta_D$ is the deviation for the yellow colour or mean deviation which is the average of the extreme deviations

Thus, where the difference in $\delta_F$ and  $\delta_C$ divided by the mean deviation is most, will have the maximum dispersive power

In Option (a) the value of ω = 3/8.5 = 0.35

In Option (b) the value of ω = 3/9.5 = 0.32

In Option (c) the value of ω = 4/14 = 0.29

In Option (d) the value of ω = 4/12 = 0.33

Therefore the maximum dispersive power is that of the values given in Option (a)

Hope this helps.