It turns out that any light wave can have lots of possible
orientations. It may be vibrating in the up and down, or maybe the side to
side. This is what we would call random polarization because the waves are randomly
polarized. (It has nothing to do with the color of the light.)
The
polarizer (invented by Polaroid) removes all of the possible orientations except one.
We could describe a polarizer as a "picket fence" . The picket
fence is actually a series of metal lines within plastic or glass.
Two polarizers at right angles to each other, will block out all orientations of light. No light would get through.
The video below shows a polarizer held in front of a camera which has another
polarizer in front of it. As the polarizer is turned, it goes from light to dark.
It appears light when the "pickets" of one polarizer match the
"pickets" of the other polarizer. The polarizer appears dark when
the two sets of "pickets" cross at right angles and allow no light through.
Glare is sun light that bounces off a horizontal flat surface, like water or the road and ends up being polarized in the same plane as the surface. This makes it difficult to see what is below the water because the glare is too bright. Driving or Fishing glasses can eliminate this glare by having polarizers that do not allow horizontally polarized light to come through. This restricts the glare and makes it easier to see road or what is under the water.
The image below shows you the effects of removing glare by using a vertically aligned polarizer. Notice how the polarized side has much less glare. You can actually see more of the inside of the car. Also the bright spot on the hood is gone. (Click on the photo to see a QuickTime movie with several more comparisons between a vertically and horizontally aligned polarizer.)
©1999 Science Joy Wagon