Optics Question 831
Question: An isosceles prism of angle $ 120{}^\circ $ has a refractive index 1.44. Two parallel monochromatic rays enter the prism parallel to each other in air as shown. The rays emerge from the opposite faces
Options:
A) are parallel to each other
B) are diverging
C) make an angle $ 2[ si{{n}^{-1}}( 0.72 )-30{}^\circ ] $ with each other
D) make an angle $ 2si{{n}^{-1}}(0.72) $ with each other
Show Answer
Answer:
Correct Answer: C
Solution:
[c] Applying Snell’s law at P, $ \mu =\frac{\sin r}{\sin 30{}^\circ } $
$ \sin r=\frac{1.44}{2}=0.72 $
$ \therefore \delta =r-30{}^\circ ={{\sin }^{-1}}( 0.72 )-30{}^\circ $
$ \therefore $ The rays make an angle of $ 2\delta =2[{{\sin }^{-1}}(0.72)-30{}^\circ ] $ with each other.
