Simplification of Light
Light is one of the Electromagnetic Waves that is visible to us. The electromagnetic wave theory is the most complete classical theory of the behavior of light.
However, the EM wave interpretation can be cumbersome and overkill for many problems. Thus, we simplify light to a scalar light wave. We can simplify this even further to a simple light ray. A light ray is simply a straight line with a direction.
We can make this simplification because when light interacts with materials several times larger than its wavelength, it acts like a ray and can be considered as a straight line.
The Laws of Geometric Optics
The Plane of Incidence
The plane of incidence is the plane that contains the incident ray, the transmitted ray, the reflected ray, and the normal vector to the plane of the surface such that they intersect at the surface.
The Law of Reflection
The law of reflection states that the angle of reflection will always equal the angle of incidence:
The law of reflection is the reason we can see things from all angles. Everything we interact with has a relatively rough surface on the microscopic level, so the light is reflected everywhere. This is often called diffuse lighting.
The Law of Refraction (Snellβs Law)
Snellβs Law is covered fully in Snellβs Law