Question

A prism $(\mu =1.5)$has the refracting angle of 30°. The deviation of a monochromatic ray incident normally on its one surface will be (sin48° 36' = 0.75)

• A. 18° 36'
• B. 20° 30'
• C. 18°
• D. 22°1'

Answer 1

The correct option is A 18° 36'

For surface $AC\frac{1}{\mu }=\frac{sin{30}^{\circ }}{sine}\Rightarrow sine=\mu sin{30}^{\circ }$

$\Rightarrow sine=1.5\times \frac{1}{2}=0.75$

$\Rightarrow e=si{n}^{-1}\left(0.75\right)={48}^{\circ }{36}^{\prime }$

From figure $\delta =e-{30}^{\circ }$

$={48}^{\circ }{36}^{\prime }={18}^{\circ }{36}^{\prime }$