If light travels from air into water and bends toward the normal, what phenomenon is this?

• A. Reflection
• B. Refraction
• C. Absorption
• D. Dispersion

Answer: (B)

Light bending as it passes from air into water is refraction. This happens because light travels at different speeds in different media. Entering water, a denser medium, slows down, so the path changes and the ray bends toward the normal—the line perpendicular to the boundary. Snell's law describes this change: n1 sin(theta1) = n2 sin(theta2). Since the refractive index of water is greater than that of air, the refracted angle theta2 is smaller, placing the ray closer to the normal. Reflection would be a bounce off the surface, absorption means the light is taken up by the medium, and dispersion is the separation of light into colors due to wavelength-dependent speeds, which isn’t what’s described here.