Question

Commercial unit of electric energy is kilowatt hour (kWh). Convert 1 kWh into Joule.

Answer 1

$1kWh=\left(1kilowatt\right)\left(1hour\right)$
$=(1\times {10}^{3}watt)\left(1hour\right)$

We know

$1watt=1J{s}^{-1}$

So,

$1kWh=\left(1000J{s}^{-1}\right)(1\times 60\times 60s)$
$=36\times {10}^{5}J$

$=3.6\times {10}^{6}J$

Thus, $1kWh$ in Joules is equal to $3.6\times {10}^{6}J.$