The Ray Model of Light

The ray model of light consists of several components that help you understand a diagram. They are:

• a light ray: a straight line with an arrow representing the direction and straight-line path of light.
• when light rays are used to determine where light will go when it strikes an object, it is called geometric optics.
• the light ray that is emitted from a source and strikes an object is called the incident ray. 
• a transparent material is a material that allows light to pass through it easily, so that objects behind it are clearly seen.
• a translucent material is a material that allows some light to pass through, but the object is not seen clearly on the other side (such as frosted glass or sunglasses).
• an opaque material is a material that does not let any light through at all. All incident light is either reflected or absorbed.
• an image is a reproduction of an object using light.
• a mirror is a reflective surface.
• reflection is the bouncing back or incident light.
• a plane mirror is a flat mirror.
• the reflected ray is the ray that bounces off the mirror.
• the normal is a line that is drawn perpendicular (or at a right angle) to the reflective surface, and is drawn at the point where the incident ray hits the surface.
• the angle of incidence, also called Ө_i, (theta i), is the angle between the incident ray and the normal.
• the angle of reflection is the angle between the reflected ray and the normal. It is also called Ө_r.