When the speeds of two media are identical, which statement is true about refraction?

When the speeds of two media are identical, which statement is true about refraction?

• A. No refraction occurs, angles are equal, wave travels straight ahead
• B. Refraction occurs, angles are equal, wave travels straight ahead
• C. No refraction occurs, angles are unequal, wave travels along the boundary
• D. Refraction occurs, angles are unequal, wave travels along the boundary

Answer: (A)

When two media have the same wave speed, there’s no change in how the wave travels across the boundary. In Snell’s law, equal speeds mean equal refractive indices, so sin of the incident angle equals sin of the transmitted angle. That makes the two angles equal, and the wave continues straight through without bending. Since the frequency stays the same across the boundary, the wavelength would also be the same on both sides. So there is no refraction, and the path remains at the same angle relative to the boundary.

When two media have the same wave speed, there’s no change in how the wave travels across the boundary. In Snell’s law, equal speeds mean equal refractive indices, so sin of the incident angle equals sin of the transmitted angle. That makes the two angles equal, and the wave continues straight through without bending. Since the frequency stays the same across the boundary, the wavelength would also be the same on both sides. So there is no refraction, and the path remains at the same angle relative to the boundary.