A monochromatic ray of light is incident normally on a thin prism of refracting angle A . The ray is deviated through an angle \((1 \cdot 15)^{\circ}\) in passing through the prism. The ray reflected internally from the second face emerges from the first face making an angle of \((6 \cdot 3)^{\circ}\) with the incident ray. The refractive index of the prism is

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.