Electrical Power Dissipation

Question

An electric heater rated to carry 5 amperes operates across a 220 volt mains supply in a kitchen, so how much power does it consume?

RankGuru · Accepted Answer

Electrical power delivered to a resistive device is the product of the voltage across it and the current through it, written as $P = VI$, a formula presented in NCERT Class 12, Chapter 3 (Current Electricity). Substituting the operating values, $P = 220 	imes 5 = 1100$ W. This is the rate at which electrical energy is converted into heat in the heating element. The option 44 W wrongly divides the voltage by the current, which would give resistance-like units, not power. The option 225 W simply adds voltage and current, an operation with no physical meaning since they carry different units. The option 215 W subtracts current from voltage, which is equally meaningless dimensionally. A magnitude check confirms plausibility: a kitchen heater drawing several amperes at mains voltage is expected to consume on the order of a kilowatt, and 1100 W is a realistic rating, while watts as volts times amperes is dimensionally correct.

Electrical Power Dissipation

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