(a) A ray of light is incident on one face of a triangular glass prism of refractive index $n$ and is refracted out from the opposite face. Deduce the expression for refractive index of glass prism in terms of the angle of minimum deviation and angle of the prism. Write the condition on $n$ for refraction to take place on the opposite face. OR (b) State Huygens principle. Using it, draw a diagram and discuss the case of refraction of plane wave of light from a rarer medium to a denser medium at their plane interface. Hence derive Snell's law.

Year	Paper Code	Set	Position
CBSE 2025	Series Other	Set 1	Question 33
CBSE 2025	Series Other	Set 1	Question 31
CBSE 2025	Series Other	Set 1	Question 32

• Step 1: Stating the fundamental formula / law statement (+1 Mark)
• Step 2: Intermediate mathematical substitution or proof steps (+1 Mark)
• Step 3: Correct final value or conclusion with mandatory SI units (+1 Mark)