An electric motor operator 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.

Options

A. 0.54
B. 5.4
C. 54
D. 540

Answer

C

Explanation

Power consumed by electric motor –
`P_(in) = VI = 15 xx 5 = 75 W = 75J//s`
`P_("out") = 60 W = 60 J//s`
Energy loss `= 75-60 = 15 J//S`
Loss in one hour `= 15 xx 60 xx 60 = 54 kJ`