Question

an electric heater of power 3 Kilowatt is used for 10 hour how much energy does it consume express your answer in kilowatt hour and joule

Answer 1

energy is product of power and time
=3×10
=30kwh

Answer 2

In 1 s =
$3 \times 10 {}^{3} \\ \\ \: \\ \: in \: 10hrs \: = 3 \times 10 {}^{3} \times 60 \times 60 \times 10 = 108 \times 10 {}^{4} watt$
= 1080KWatt