PHYSICS · Subjective · CBSE · Physics · Ray Optics and Optical Instruments · Ray Optics and Optical Instruments
Problem
During a laboratory investigation, a student records that a ray travelling from an unknown liquid into air has a critical angle of 42∘.
(i) Show how the student can use this observation to obtain the refractive index of the liquid.
(ii) A glass plate of refractive index 1.65 is gently placed on the surface of the same liquid so that the ray now passes from the liquid into glass and then out into air. For an incidence angle of 50∘ in the liquid, calculate the angle that the emergent ray makes with the normal in air.
(iii) Comment on whether total internal reflection can occur at the liquid–glass boundary for any ray inside the liquid. Justify your answer with numerical support.