Polarization

Hasegawa, Harry                          Lawndale Community Academy
18W780 14th St.                          762-7745
Lombard, IL 60148
620-7945
 
Objectives

1) Students will learn basic facts of polarization
2) Demonstrate some phenomenological activities illustrating
   interference patterns.
3) Make "take-home" project of the interference pattern.

Equipment and Materials

Microprojector               Clear plastic box
Crystals of:                 Polarizing films
            sugar            Cellophane tape
            epsom salt       Microscope slides
            salol
            mica
            salt

Recommended Strategies

Review light waves and experiment with polarizing film.
Demonstrate the nature of polarized light showing that polarized light
travels in a single plane instead of the 360 degree of unpolarized
light.

Demonstrate the interference pattern of various crystals which are 
placed between two polarized films on the microprojector.
     When light passes through a polarized film, the many color rays
     (or wave lengths) which make up the white light travel at various
     velocities and break up or interfere with another ray .

     A wave length or white light is then subtracted and shows the 
     complementary color-- the color that is left when white light 
     is subtracted. This is the interference pattern.

Demonstrate light reflecting from a smooth surface such as plastic 
is polarized. The reflecting light comes to the eye in a single plane.

Show that many digital read-outs are also polarized.

Have students make a take-home project demonstrating interference
patterns by placing a number of small pieces of cellophane tapes
randomly on a microscope slide. Then view the slide placed between
two polarizing films.