A triangular glass prism ABC is immersed completely in water
PHYSICS · Subjective · CBSE · Physics · Ray Optics and Optical Instruments · Ray Optics and Optical Instruments
Problem
A triangular glass prism ABC is immersed completely in water. A monochromatic ray enters the prism normally at face AB, strikes face AC at an angle of 40∘ to the normal and finally leaves the prism through face BC into water.
(i) Derive an inequality involving the refractive index n of glass (with respect to water) that must be satisfied for the ray to undergo total internal reflection at face AC.
(ii) Hence calculate the minimum value of the absolute refractive index of glass (with respect to vacuum) required for total internal reflection at AC. (Refractive index of water is 1.33.)
(iii) If the actual refractive index of the glass used is 1.52, find the critical angle for the glass–water boundary and state whether the condition obtained in part (i) is fulfilled.