Polarization

What is polarization?

            Before understanding how polarization works, one must understand the properties of light.  Contradictory to one’s normal conception of waves, light vibrates in two planes, not just one.  This is shown in the diagram to the right, labeled “Diagram 1”.  A light wave which is vibrating in more than one plane is referred to as unpolarized light. Light emitted by the sun, by a lamp in the classroom, or by a candle flame is unpolarized light.  Polarization is the process by which light is limited to a single plane of vibration.  This is seen below in Diagram 2.

Diagram 2

An interesting concept happens when two Polaroid filters are placed perpendicular to each other.  This is illustrated in Diagram 3 below.

Diagram 3

Light that is on the vertical plane will be able to easily pass through the vertical spaces on the fence, but light that is on the horizontal plane will not be able to pass through the vertical spaces on the fence.  All that is left in this situation is light on the vertical plane, therefore.  However, when both vertical and horizontal fences are placed together, all light is blocked because both the vertical and horizontal planes are blocked.

How and why does polarization occur?

There are several other ways that polarization occurs.  One is illustrated above, in Diagram 1, where a Polaroid filter is used to block out a plane of light.  Another is when light reflects off of a surface at just the right angle, light is broken down into only one plane.  This is illustrated in Diagram 4.  Automobile drivers can be familiar with this phenomenon when glare appears on asphalt.  Fishermen are also familiar with this when they are unable to see fish underwater because light polarizes off the water surface.

Diagram 4

Another way that polarization occurs is through the refraction of light through a surface, this is shown in Diagram 5.  As light enters the surface, it is split into its two planes.  They then exit at different points in the material.

Diagram 5

Our projects on Polarization

Polaroid Island

Chromo-Kinetic Art

References:

http://www.glenbrook.k12.il.us/gbssci/phys/Class/light/u12l1e.html

http://nths.newtrier.k12.il.us/academics/math/Connections/connections.htm