The refractive index of glass with respect to water is and that of glass with respect…
PHYSICS · Subjective · CBSE · Physics · Ray Optics and Optical Instruments · Ray Optics and Optical Instruments
Problem
The refractive index of glass with respect to water is 1.20 and that of glass with respect to air is 1.60. A parallel-sided glass plate is submerged horizontally in water. A ray originating in water is incident on the water–glass boundary. After refraction into the glass it strikes the glass–air boundary at exactly the critical angle for the glass–air interface.
(i) Calculate this critical angle.
(ii) Determine the angle of refraction that the ray makes with the normal at the water–glass boundary.
(iii) Hence find the angle of incidence in water that produces the above condition.
(iv) Explain why a slight increase in this incident angle would lead to total internal reflection at the glass–air boundary.