1. Light is an ElectroMagnetic Wave
EM waves are created by vibrating electrons
Electrons low mass allows for very high frequencies
Radio waves (105 Hz) up to Gamma Rays (1021 Hz)

2. Polarization
Non-polarized light is vibrating in all orientations (drawn like this )
Some orientations can be eliminated
Eliminated with polarizing filter
Eliminated thru reflection
The human eye by itself cannot detect whether is light is polarized or not. You need a polarizing filter to be able to tell.

3. Polarization with a polarizing filter

4. Polarization thru reflection

5. Reflection and Refraction

6. The Law of Reflection
Angle of incidence = angle of reflection (θi = θr)

7. Reflection
Energy (light) can be totally reflected or partially reflected
Example of both is seen in a car’s rear view mirror
Light is partially reflected off the glass surface while totally reflected off the mirrored surface

8. Mirror tilted to night mode
Light from behind
4 % light reflected from glass over your head
96% light reflected to driver’s eyes
Mirror in day mode
Mirror glass
Mirror tilted to night mode
Light from behind
4 % light reflected from glass to your eyes
96% light reflected below driver’s eyes
Mirror glass

9. Reflection off of glass
Reflection is about 4% of the light
With no light coming from behind, reflection is easily seen

10. The law of reflection holds true for curved surfaces as well

11. Regular and Diffuse Reflection
Regular reflection is also called specular
reflection. It comes from smooth surfaces.
Smooth means topography varies less than
1/8 λ.
Diffuse reflection reflects light in all directions,
allowing the object to be seen from all angles.

12. If a surface is smooth depends on incident wavelength
Paper is not smooth to visible light
(λ = 400nm – 700nm)
You get a diffuse reflection of light off of paper.
This large antenna dish is smooth to radio waves (λ > several meters)
You get a specular reflection of radio waves off of this dish.
A surface is smooth if contours are less than 1/8 λ

13. Focal Length of Concave Mirror
Parallel rays reflecting off the concave mirror converge at the focal point

14. Specular reflection off of curved surfaces
Convex surface
Concave surface
In a concave mirror, images are upside down beyond the focal point and right side up inside the focal point
In a convex mirror, images are upright and smaller.

15. Inside and the back of a spoon

16. Refraction
Refraction is the bending of a wave (its direction is changed)
It is caused by a change in the speed of the wave as it enters a new medium
Animation of refraction

17. Apparent depth
Refraction causes depth of object in water to appear less than it actually is

18. Atmospheric Refraction (Mirage)

19. Pumpkin Sun/Moon

20. Dispersion

21. The Rainbow

22. Total Internal Reflection