Chapter 26 Geometrical Optics

Outline
26-1 The Reflection of Light
26-2 Forming Images with a Plane Mirror
26-3 Spherical Mirror
26-4 Ray Tracing and the Mirror Equation
26-5 The Refraction of Light
26-6 Ray Tracing for Lens
26-7 Thin Lens Equation
-5 The Refraction of Light
Refraction:
Light will change the motion direction when it travels from one medium
to the other. This phenomenon is called refraction.
Definition of the index of refraction in a medium, n >=1
= (26 ?10)
v
n c
Where, v is the speed in the
medium. C is the speed in
vacuum.
Refraction is caused by the
difference of speeds in two

Total Polarization
Light reflected from a nonmetallic surface is generally polarized to some
degree. At a special angle of incidence, Brewster’s angle, ?B is :
Complete Polarized reflection: Reflected light is completely polarized
when the refracted beams are at a right angle with the reflection beam.
The direction of polarization is parallel to the reflection surface.
26-6 Ray Tracing for Lenses (Find the image position)
Lens: a lens is a piece of glass or other transparent material that
converges or diverges the light beams for imaging purpose.
Two kinds of lenses: Converging lens and Diverging lens (identifying by
comparing the thicknesses of the center and edge)