Light: Geometric Optics

The Ray Model of Light

The ray model of light assumes that light travels in straight-line path called rays.

Reflection

For flat surfaces, it is found that the incident and reflected rays lie in the same plane with the normal to the surface.

Law of Reflection

The angle of incidence equals the angle of reflection.

Diffuse reflection Specular reflection

Image Formation by a Plane Mirror

For a plane mirror the image distance (distance from mirror to image) equals the object distance.

Real and Virtual Images

How tall must a full-length mirror be?

A woman 1.60m tall stands in front of a vertical plane mirror. What is the minimum height of the mirror, and how high must its lower edge be above the floor, if she is to be able to see her whole body? Assume her eyes are 10 cm below the top of her head).