When discussing light refraction, what does the term "normal" refer to?

In the context of light refraction, the term "normal" specifically refers to the line that is perpendicular to the surface at the point where the light ray strikes. This line is crucial in understanding the behavior of light as it crosses the boundary between different media, such as air and glass or water.

When light rays travel from one medium to another, they change speed and direction, an effect known as refraction. The angle at which the light hits the surface is called the angle of incidence. The normal line serves as a reference point to measure this angle as well as the angle of refraction. When analyzing these angles, using the normal simplifies calculations and helps apply Snell's Law effectively, which describes how light bends when entering a new medium.

The average speed of light, the angle of incidence, and the wavelength of light are important concepts in optics but do not specifically describe what the "normal" refers to in the context of refraction. Understanding the role of the normal line in the refraction process is crucial for studying how light behaves when interacting with different materials.