It is said that alloys are used as heating elements in heaters because they generate more heat due to higher resistance than pure metals. But, higher resistance means lower current flows through the alloys. According to the formula H=I²Rt, heat is directly proportional to the square of current and to the resistance. In this way, heat depends more on current supplied than on resistance(bcoz it is directly proportional to sq of current). So, practically aplying this concept, metals should get more heated than alloys in a given time. Why does this difference arise??

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Solution

Alloys are used as heating elements in heaters because they have high melting point and high resistivity. A heating element should not only produce large amount of heat but it also should have high melting point. Alloys have high melting point, therefore it is used as heating element instead of metal.

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