Explain Working of an electric bulb in 100-150 words
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Answer:
An electric bulb is a device which produces light when electricity is passed through its terminals. The bulb has two thick contact wires in the center with a thin wire attached between them. ... When electricity is passed through the terminals of the bulb, the filament gets heated up and produces light.
Long before the light bulbs were invented, lamps (lanterns) with animal fat, wax, and vegetable oil were used to illuminate homes and surroundings. In 1800, an English scientist named Sir Humphry Davy made the first electric light using batteries (his self-invention) and a piece of carbon, but his light bulb had a very short life. In 1860, Sir Joseph Swan developed an incandescent light using carbon filament, but it also burnt up quickly due to high electric current.
Thomas Alva Edison started working on the light bulb. He experimented with thousands of filaments, and in 1879 produced a first commercial incandescent lamp with a very high-resistance filament to increase the life of the light. He used an oxygen-free glass bulb. Oxygen helps to burn the carbon filament fast, but in the oxygen-free bulb, the filament will not burn. It only glows, and hence is derived the name “incandescent” light.
In 1990, William Coolidge invented the tungsten filament which has a very high melting point and thus an even longer life than the carbon filament.