Answer to Question #113763 in Electric Circuits for Lucille Napper-Green

Question

The electrical circuit has 3 devices each plugged into household powerpoint. Device A has a resistance of 1.0 Ω, device B has a resistance of 3.0 Ω and device C has a resistance of 6.0 Ω. If all three devices are turned on for 15 minutes, what will be the Total Energy Consumption of the 3 device.

Answer 1

$P=P_a+P_B +P_C;P=\frac{U^2}{R_A}+\frac{U^2}{R_B}+\frac{U^2}{R_C};\\P=\frac{14400}{1}+\frac{14400}{3}+\frac{14400}{6}=21600W=21.6kW$

If household powerpoint is 220V then

$P=P_a+P_B +P_C;P=\frac{U^2}{R_A}+\frac{U^2}{R_B}+\frac{U^2}{R_C};\\P=\frac{48400}{1}+\frac{48400}{3}+\frac{48400}{6}=72600W=72.6kW$

Answer: the Total Energy Consumption is equal to 21.6kW or 72.6kW