What is the advantage of using fluorescent bulbs over incandescent bulbs?

Incandescent bulbs work by conducting an electric current along a filament made of a long, thin piece of tungsten metal. The filament must be heated to temperatures of about 2,300 degrees Celsius to glow and emit a white-hot light. But the process transforms only 5 percent to 10 percent of the electricity used into visible light. The rest is transformed into heat, which can eventually increase the temperature of a room.

CFL bulbs, on the other hand, are made of glass tubes filled with gas and a small amount of mercury. The amount is so small that an old-fashioned glass thermometer holds 100 times as much mercury as one CFL bulb. Light is emitted when mercury molecules in a CLF bulb become excited by electricity running between two electrodes at its base. The mercury emits an invisible ultraviolet light that becomes visible when it hits the white coating inside the CFL bulb.

Basically, based on how they both work, fluorescent bulbs last longer and do not release as much heat as incandescent bulbs which means it's also better for the environment. 

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