Ray

Definition

A ray is a straight line that represents the path along which light energy travels. It is used in geometric optics to model the behavior of light when it encounters boundaries such as mirrors and lenses.

5 Must Know Facts For Your Next Test

1. A ray is used to simplify the study of light propagation.
2. Rays can be reflected, refracted, or absorbed depending on the medium they encounter.
3. In geometric optics, the law of reflection states that the angle of incidence is equal to the angle of reflection.
4. The law of refraction (Snell's Law) governs how rays bend when passing between different media.
5. Rays are essential for understanding image formation in optical systems like cameras and telescopes.

Review Questions

• What happens to a light ray when it passes from air into water?
• How does the angle of incidence compare to the angle of reflection for a light ray hitting a mirror?
• What principle explains the bending of light rays as they enter a different medium?

Related terms

Reflection:

The change in direction of a light ray when it bounces off a surface.

Refraction:

The bending of a light ray when it passes from one medium to another due to a change in its speed.

Snell's Law:

A formula that describes how rays bend during refraction: $n_1 \sin(\theta_1) = n_2 \sin(\theta_2)$ where $n$ represents the refractive indices.