An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
Solution and Explanation
Rate of heat produced by a device is given by the expression for power as, \(P= I^2R\)
Where,
Resistance of the electric heater, \(R= 8 \ Ω\)
Current drawn, \(I = 15 \ A\)
\(P= (15)^2 \times 8 \)
\(P= 1800 \ J/s\)
Therefore, heat is produced by the heater at the rate of \(1800 \ J/s.\)
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Concepts Used:
Electric Power
Power is defined as the rate of doing work. Electric power is the rate at which electrical energy is transferred through an electric circuit, i.e. the rate of transfer of electricity. The symbol for Electric Power is ‘P’. SI unit of electric power is Watt.
Electric Power Formula
P = VI
From Ohm's Law, V = IR
Hence, Power can also be expressed as P = I2R