Digression on negrescence of incandescence
Posted: Sat Sep 21, 2013 5:45 pm
Negrescence due to the cooling of an incandescent light bulb takes about a tenth of a second.wonderboy wrote:
"I'm so fast that last night I turned off the light switch in my hotel room
and was in bed before the room was dark"
Muhammad Ali, faster than the speed of light?
Assuming the switch is ~3m away Ali must move ~30 m/s or ~10-7 the speed of light.
http://dx.doi.org/10.1063/1.1710410 wrote:
Time Constants of Incandescent Lamps
J. Appl. Phys. 9, 209 (1938)
W. E. Forsythe, M. A. Easley, and D. D. Hinman
Incandescent Lamp Department, General Electric Company, Nela Park, Cleveland, Ohio
<<Candescence and nigrescence curves are shown for a number of tungsten lamps, vacuum and gas‐filled, ranging in size from the automobile lamps up to the 30‐volt, 30‐ampere lamp and the 1000‐watt photoflood lamp. Data are given for similar filaments mounted in vacuum lamps and in lamps filled with argon, nitrogen, hydrogen, and helium. The filament of a vacuum lamp reaches 90 percent brightness on heating in time t=0.060I; 10 percent brightness on cooling in time t=0.022I; for gas‐filled lamps, t=0.15I and t=0.070I, respectively. (I is the normal operating current of the lamp.)>>