Snell's law governs refraction from liquid to air

Steps:

• Refractive index of liquid is 1.4 (relative to air, where n_air = 1).
• Apply Snell's law: n_liquid sin i = n_air sin r, so 1.4 sin i = sin r.
• From diagram, angle of refraction r in air is 57°; sin 57° ≈ 0.8387.
• sin i = 0.8387 / 1.4 ≈ 0.599; i = arcsin(0.599) ≈ 37°.

Why B is correct:

• Snell's law precisely calculates i = 37° using the given n = 1.4 and r = 57° from the diagram.

Why the others are wrong:

• A: Assumes smaller r ≈ 32°, underestimating refraction spread.
• C: Matches r ≈ 66°, overestimating incidence angle.
• D: Matches r ≈ 82°, ignoring proper sin r / n ratio.

Final answer: B