How does an electric bulb glow?

There are two types: fluorescent and incandescent lightbulbs.

An incandescent lamp uses heat generated by an electric current. The wire heats up when an electrical current passes through it. The filament (or wire) heats up to the point that it glows and emits light. The filament of every day incandescent light bulbs is made from tungsten. The tungsten filament will quickly burn if exposed to oxygen. Therefore, it must be sealed in a glass bulb that is either evacuated or filled by a gas that will not let it burn.

The fluorescent lamp is another common type of light. A fluorescent lamp is made up of a tube of glass filled with argon and toughened with mercury. The atoms in the gas absorb energy from an electrical current and emit it as heat. The tube’s interior is then coated with a protective phosphor. The phosphor glows and gives off the visible light.

Fluorescent lamps do not require high temperatures to produce light like incandescent bulbs. Heating the incandescent bulb requires energy. However, a large portion of that energy is lost to heat and not light. A larger proportion of energy in the fluorescent lamp is radiated by light.

 

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