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Question
An electric filament lamp is connected to a supply of voltage higher than the recommended value. Give reasons, why compared with a normal performance, the lamp emits a brighter light and its life is shortened.
Solution
The lamp will have the filament of a particular resistance. If it is connected to a supply of higher voltage, the heat energy produced in it will be more (since H = V2t/R), i.e., the filament will get more heated so it will glow more and the lamp will emit a brighter light. On the other hand, due to Excess heating, the filament may vaporize and so its life may shorten.
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