Question

A d.c electric motor consumes 36 MJ when connected to a 250V supply for 1 hour. Find the power rating of the motor and the current taken from the supply.

Answer 1

$E=36\times10^6 J$ - energy

$U=250 V$ - voltage

$t=1$ hour $=3600$ seconds

Power rating of motor $P=E/t=10kW$

Power rating equal $P=UI$ , where $I$ - current taken from supply, which equals $I=P/U=40A$