Light is electromagnetic radiation. Light is the portion of the electromagnetic spectrum that is visible to the human eye. Many aspects of the physical behavior of light can be explained in terms of ray theory. A ray of light is a straight path that the light travels in from one point to another. Reflection and refraction are two phenomena readily explained by ray theory. Consider a light ray impinging on an object.A portion of the light wave is redirected away from the object, while the other portions are absorbed by the object and transmitted through it. Reflected light is the portion of the light wave redirected away from the object. Light travels at different speeds in different media. When a ray of light is transmitted through two materials, the line of travel of the light wave is changed at the interface along the centerline of the wall.
By Gary Conner
By George N Bullen FSME