Question

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.

Answer 1

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 $1800 \ J/s.$