Presentation on theme: "Incandescent Light Featuring Louie the Lightning Bug Melissa Long Allison M c Coy Junior Lab December 10, 2003."— Presentation transcript:
Incandescent Light Featuring Louie the Lightning Bug Melissa Long Allison M c Coy Junior Lab December 10, 2003
History of the Light Bulb 70,000 BC - first lamp invented Humphry Davy, an English chemist, invented the first electric light Henricg Globel, a German watchmaker, invented the first true light bulb Henry Woodward and Matthew Evans patented the light bulb Thomas Alva Edison invented first successful incandescent light bulb Tungsten was first used for light bulb filaments
Blackbody Radiation The spectrum of a blackbody depends only on the temperature of the object. Incandescent Lights give off blackbody radiation.
Incandescent Light ÛElectric current passes through metallic filament ÛFilament heats producing visible light ÛFilament enclosed in evacuated glass bulb or a bulb containing an inert gas Û
Halogen Lamp Û Step 1: Tungsten atoms evaporate from the hot filament and move toward the cooler bulb-wall. Û Step 2: Tungsten, oxygen and halogen atoms combine at the bulb- wall to form tungsten oxyhalide molecules. Û Step 3: The bulb-wall temperature keeps the tungsten oxyhalide molecules in a vapor. The molecules move toward the hot filament where the higher temperature breaks them apart. Û Step 4: Tungsten atoms are re- deposited on the cooler regions of the filament. Û W(s) + 3Cl 2 (g) WCl 6 (s) WCl 6 (s) W(s) + 3Cl 2 (g) heat Û
Wavelength of Our Light Sources
Louie The Lightning Bug brought to you by CIPCO’s Electric Universe:The Power of Learning (http://cipco.electricuniverse.com/html/index.html) zebu.uoregon.edu/~imamura/ 123/lecture-1/cmbr.html