A prism is made up of flint glass whose dispersive power is 0.053. Find the angle of dispersion if the mean refractive index of flint glass is 1.68 and the refracting angle of prism is 3°.

0.108°

As the refracting angle is small deviation = (µ – 1) A

angle of dispersion = $D_v-D_r$

$=(m_v-1)A-(m_r-1) A$

$=\left(m_v-m_r\right) A$

$=\left(\frac{\mu_v-\mu_r}{\mu_{\text {mean }}-1}\right) A\left(\mu_{\text {mean }}-1\right)$

$=w A\left(m_{\text {mean }}-1\right)$

$=(0.053) \times 3 \times(1.68-1)=0.108^{\circ}$