St. John, Thomas M. (Thomas Matthew), b. 1865 · New York, T. M. St. John · leaf 135
forcing a strong currentthrough it, but this shortens its life. The Current used for incandescent lamps has to be strong enough to force its way through the filament and Fig. 200. produce a heat sufficient to give a … LIGHT PRODUCED BY INCANDESCENT EAMP. 133 good light. The usual current has 50 or no volts,although small lamps are made that can be run by twoor three cells. If the voltage of the current is less thanthat for which the lamp was made, the light will be dim.The filament can be instantl} burnedout by…
Electricity
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