Question

A glass cylinder is placed at top of a surface as shown. A source of light lies on its axis at position $S$. The light rays from source $S$ strike the upper surface of the glass and enter into the glass medium of refractive index $1.5$. Then chose the correct statement regarding the rays entering into glass cylinder and striking curved surface.

• A. Total internal reflection will happen for the rays striking near top half of the cylinder
• B. Total internal reflection will happen for the rays striking near the bottom half of cylinder on its curved surface
• C. Total internal reflection will not take place for any of the rays striking the curved surface
• D. Total internal reflection will take place for all the light rays striking at curved surface

Answer 1

The correct option is D Total internal reflection will take place for all the light rays striking at curved surface

For any material having refractive index $\mu >\sqrt{2}$, light incident at any angle on curved surface will undergo TIR.

As from the question, $\mu =1.5>\sqrt{2}(=1.414)$
So, all the rays that strike the cylindrical curve surface will undergo total internal reflection.

Hence, option $\left(d\right)$ is correct.