TV and Florescent Lights

Imagine if your computer monitor worked by incandescence: it would probably be hot enough to cook food! Thankfully, there's another way of producing light: luminescence. Three of the most common applications of luminescence are in computer monitors, televisions, and florescent lights. Both of these rely on phosphors, special chemicals that release light when excited by electricity, radiation, or other methods.

Florescent lights actually employ two types of luminescence, electroluminescence and photoluminescence. First, a current is passed through an ionized gas, usually mercury vapor and argon. This causes the atoms to release ultraviolet light. The ultraviolet light is then absorbed by a phosphorescent coating on the inside surface of the lamp. This coating remits the light in the visible spectrum where we see it.

By contrast, televisions and computer monitors stimulate phosphors to emit light directly. A screen is comprised of thousands and thousands of red, green and blue phosphors. Three extremely high voltage electron beams sweep across the screen many times per second, giving energy to the phosphors making them glow and thus produce an image. Your eye will mix the red, green and blue phosphors and you will see any of a rainbow of colors, depending on the brightness of each component color.

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