When light changes direction at the boundary between two materials, the process is called ______.

When light changes direction at the boundary between two materials, the process is called ______.

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

Answer: (C)

Light changes direction at the boundary between two materials because its speed changes in the new material. This bending of the light ray as it passes from one substance to another is called refraction. The amount and direction of the bend depend on how fast light travels in each material and the angle at which the light hits the boundary. A common example is a straw appearing to bend when it sits partly in water—the light is slowed as it enters the water and the path tilts toward the normal. If the light just bounces off the surface, that’s reflection; if the light is absorbed by the material, you don’t see it; diffraction is bending around edges or through narrow openings, not simply at a boundary.

Light changes direction at the boundary between two materials because its speed changes in the new material. This bending of the light ray as it passes from one substance to another is called refraction. The amount and direction of the bend depend on how fast light travels in each material and the angle at which the light hits the boundary. A common example is a straw appearing to bend when it sits partly in water—the light is slowed as it enters the water and the path tilts toward the normal. If the light just bounces off the surface, that’s reflection; if the light is absorbed by the material, you don’t see it; diffraction is bending around edges or through narrow openings, not simply at a boundary.