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Producing Light. Incandescent Lights . Heating a piece of metal until it glows Thin wire called a filament More than 80 percent of the energy in this light is produced as heat. Fluorescent Lights. Filled with a gas at low pressure
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Incandescent Lights • Heating a piece of metal until it glows • Thin wire called a filament • More than 80 percent of the energy in this light is produced as heat
Fluorescent Lights • Filled with a gas at low pressure • Inside of bulb is coated with photophosphors that emit visible light when the absorb ultraviolet radiation. • Contains electrodes at each end • Very efficient
Neon Lights • Vivid glowing colors • Glass tube filled with different gases to make different colors • Molecules collide to make the light
Sodium Vapor Lights • Tube that contains neon gas and argon gas and a small amount of sodium metal • Use in street lights • Emits a yellow glow
Tungsten-Halogen lights • Tungsten filament inside quartz bulb or tube and a gas • Filament becomes hotter than the incandescent light because of the gas
Lasers • Number of light waves are emitted at the same time. • Each atom must give the same energy • Light waves are sent from the atoms • Helium laser--red light • Laser light is coherent all traveling the same wavelength
Using Lasers • CD players • Surgincal tools • Surveyors for buildings • Measure the moons orbit • Communications
In Medicine • Used to remove cataracts, reshape the cornea and repair the retina • Laser seals off blood vessels as it cuts and reduces bleeding and scars
CD Player • Lasers are used to burn the holes into the CD so that it can play. • Laser is used to read the CD and play what is on it.