Why do we feel warm when you are standing under a 100 W filament lamp?



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An incandescent lamp has a filament that works when electricity passes through the filament. Due to the resistance of the filament there is heat generated when a current passes though it. If the power rating of the lamp is 100 W it consumes 100 W of power. The power consumed raises the temperature of the filament.

A body when heated emits electromagnetic radiation of different frequencies and the highest frequency of radiation that is emitted is determined by the temperature of the body. Heat or infrared radiation has a lower frequency than visible light. When the filament of the lamp is heated a large amount of infra-red radiation is emitted with a small amount of visible light. This is the reason why one feels warm when standing under an incandescent lamp that works solely by heating a filament. It is also the reason why lamps with a filament have a low efficiency and a large amount of the power that is consumed is used not for producing light emitted in the form of heat.


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