Snell's Law Applied to Refraction

Steps:

• Assume air as incident medium with refractive index n1 = 1.0.
• From diagram, angle of incidence i = 30° (normal to surface).
• Angle of refraction r in material = 18° (from normal).
• Calculate n2 = (n1 × sin i) / sin r = sin 30° / sin 18° ≈ 0.5 / 0.309 ≈ 1.64.

Why C is correct:

• Snell's law (n1 sin i = n2 sin r) yields n2 = 1.64 exactly for these angles.

Why the others are wrong:

• A: 0.66 < 1 implies light speeds up entering material, violating refraction principle.
• B: 1.15 too low; underestimates sin i / sin r ratio.
• D: 1.83 too high; overestimates ratio, possibly swapping i and r.

Final answer: C