Question

An electric motor operating on $15\,V$ supply draws a current of $5 \,A$ and yields mechanical power of $60 \,W$. The energy lost as heat in one hour (in $kJ$ ) is

• A. 0.54
• B. 5.4
• C. 54
• D. 540

Answer 1

Answer: (C)

54

Answer 2

Input power $=V I=15 \times 5=75\, W$ Output power $=60 \,W$ Power lost $=15\, W$ Energy lost $=15 \times 60 \times 60$ $=54000\, J =54\, kJ$