Snell's Law is used to determine which aspect of wave behavior at an interface?

• A. Incoherence
• B. Scattering
• C. Angle of transmission
• D. Wavelength in the second medium

Answer: (C)

Snell's Law describes how a wave bends when it passes from one medium into another with a different propagation speed. It gives a precise relationship between the angle the incoming wave makes with the normal to the boundary and the angle the transmitted wave makes with that same normal, determined by the refractive indices of the two media. In practical terms, the law tells you how the direction of the wave changes as it enters the second medium—the angle of transmission. It isn’t about incoherence, which concerns phase relationships; it isn’t about scattering, which involves redirection due to irregularities; and although the wavelength does change in the second medium, Snell's Law specifically governs the direction (the transmitted angle), not the wavelength itself.