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 in the figure. The rays emerging from the opposite faces.

• A. are parallel to each other
• B. are diverging
• C. make an angle of $2\left[si{n}^{-1}\right(0.72)-{30}^{\circ }]$ with each other
• D. make an angle of $2si{n}^{-1}\left(0.72\right)$ with each other

Answer 1

The correct option is C

make an angle of $2\left[si{n}^{-1}\right(0.72)-{30}^{\circ }]$ with each other

using snells law, find the angle of refraction at the other two faces of the prism, which will come to be $si{n}^{-1}\left(0.72\right)$. And finally using the sum of internal angles of a quadrilateral to be 360 degrees, get the answer.