Question

Calculate the energy in the 5 ohm resistor in 20 seconds.

(a) 21.5kJ

(b) 2.15kJ

(c) 2.15J

(d) 21.5kJ

Answer 1

The correct option is (a) 21.5kJ

For explanation I would say: The current in the circuit is equal to the current in the 5 ohm resistor since it a series connected circuit, hence I=220/(5+10)=14.67A. P=I^2R = 14.67^2*5=1075.8W. E=Pt = 1075.8*20 = 21516J=21.5kJ.