21.4. Polarization http://www.ck12.org
21.4 Polarization
Objectives
The student will:
- Understand the meaning of polarization and its mechanism.
- Understand polarization by transmission and reflection.
Vocabulary
- polarized light: Light with electric field vibrations in only one direction, also known as linearly polarized
light.
Introduction
Light is a transverse wave. Unlike sound, which pushes back and forth, it is instead comparable to a pulse or wave
that travels down a length of string. How do we know this? The key difference is that a transverse wave can vibrate
in different directions, like side-to-side compared to up-and-down. We can see this difference in light when the
direction of how we look at something changes. An example of this is shown below.
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/66600The light is blocked only when the glasses are held in a particular way because of polarization.
Polarization by transmission
All electromagnetic waves come from vibration of electric charges. Just like a wave in a string or whip, they have a
direction, like up-and-down or side-to-side, as shown inFigure21.18. The transverse orientation of the wave is the
direction of the electric field variation.
Light produced by most common sources, from stars to light bulbs to candles, has a mix of many different transverse
wave direction –up-and-down, side-to-side, and all diagonals.
Polarized light(also known as linearly polarized light) is light with electric field vibrations in only one direction.