A cross section of a light pipe made of a glass fibre of refractive index 1.68 . The outer covering of the pipe is made of material of refractive index 1.44 . What is the answer if there is no outer using of the pipe ?

Question

$\begin{array}{1 1} 0^{\circ} \;to 45^{\circ} \\ 45 ^{\circ}\;to \; 60^{\circ} \\ 0\;to \;60^{\circ} \\ 0^{\circ} \;90^{\circ} \end{array}$