How Do Light Bulbs Work?
The filament bulbs work according to Jule’s principle. When electricity passes through a conductor it generates heat depending on conductors resistance, potential difference across the conductor and intensity of current. Filament’s resistance is of such magnitude that when electricity pass through it, it heats up. The temperature is so high that the atoms starts radiating electromagnetic wave predominantly visible and infrared. In case of gas bulb the principle is based on conduction of electricity in gases in low pressure and density. In florescent bulb basically infrared is produced and falls on florescent layer of the bulb and emits light of visible range.
The old bulbs which Edison invented have an electrical current running through a tungsten wire – in an atmosphere with no oxygen in it. If there was oxygen, the tungsten wire would heat up – and oxidize and burn in half. With no oxygen, the tungsten wire gets so hot that it glows – thus producing a lot of heat and a little light. You can’t see the heat part. That’s inferred wavelength. You evolved only to see the “visible light spectrum” part.
