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
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.