"Traditional" televisions use cathode ray tubes, in which a gun fires a beam of electrons inside a large glass tube at phosphor atoms at the other end. The electrons excite the phosphor atoms, causing them to light up as pixels. The image is produces by lighting up different areas of the phosphor coating with different colors (red, green, blue) at varying intensities. While this sort of TV produces nice images, physically they are bulky. In order to increase screen size, you have to increase the length of the cathode ray tube. So, a big-screen TV of this sort will take up a lot of room.
Flat panel plama TVs on the other hand, can have large screens and only be a few inches thick. The basic idea of a plasma display is to use tiny fluorescent lights--made up of either red, blue, or green-- to form an image on the screen. Plasma refers to gas made up of free-flowing ions and electrons. When you introduce many free electrons into the gas by exerting electrical current across it, they collide with the gas' atoms knocking loose other electrons. This forms ions (an atom with a net positive charge).
In a plasma with an electrical current running through it, negatively charged particles are rushing toward the positively charged area of the plasma, and positively charged particles are rushing toward the negatively charged area. While the particles are bumping into each other, these collisions excite the gas atoms (xenon and neon) in the plasma causing them to release photons of light. Most of light released is UV light, which is invisible to the human eye. BUT this UV light can be used to produce light in the visible spectrum.
(More under the fold...)
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