Which statement best defines refraction?

• A. The reflection of light off a surface.
• B. The bending of light as it changes speed entering a new medium.
• C. The transmission of light through a material.
• D. The absorption of light by a material.

Answer: (B)

Refraction happens because light travels at different speeds in different media. When a beam hits a boundary and enters a medium where its speed is different, its velocity changes and the light path bends. This change in direction at the boundary is refraction. The amount of bending depends on the media’s optical densities and is described by Snell’s law. For example, light slows and bends toward the normal when entering water from air, and speeds up and bends away when leaving water into air. The other ideas describe reflection (light bouncing off a surface), transmission (light simply passing through), or absorption (light energy being taken up by the material).