What is the phenomenon called when light changes direction as it passes through different mediums?

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

Answer: (B)

The phenomenon where light changes direction as it passes from one medium to another is known as refraction. This occurs because light travels at different speeds in different mediums; for instance, light moves more slowly in water than in air. When light encounters a boundary between two different materials, such as air and glass, it bends at the boundary due to this change in speed. The amount of bending depends on the angle at which the light hits the surface and the indices of refraction of the two mediums involved.

Refraction is responsible for many optical effects, such as the bending of a straw in a glass of water, the formation of rainbows, and the way lenses focus light. Understanding this concept is crucial in fields like optics, photography, and various applications involving lenses and prisms.