1. Light Diffraction, Interference and Polarization

2. Diffraction Diffraction is the bending of any wave including light.
Easily seen when looking at shadows
Every shadow’s edge is slightly blurry due to bending of light waves around the object

3. Problems with diffraction
Microscopes that use light cannot see objects that are smaller than wavelength of light
Diffraction makes the object very blurry
Electron microscopes are used instead to avoid diffraction.

4. Interference
When two waves interact, the waves may join to make a larger wave or cancel each other out

5. Diffraction Gratings
An object with a multitude of closely placed slits.
Separates light into the spectrum of colors
Examples
Bird’s feathers
CD/DVD discs

6. Interference Thin films of liquid can act like diffraction gratings
Examples
Soapy water
Gasoline on water

7. Polarization The alignment of transverse waves along the same axis.
Occurs when the light reflects off a shiny surface
Glass windows
Water

8. Uses of Polarization Sunglasses 3-d movies glasses
Polarized sunglasses have closely spaced vertical slits.
This blocks light reflected from pavement or water sources
3-d movies glasses
One eye is vertically polarized; the other is horizontally polarized.