Question

Find the kilowatts hours used if a 500-watt appliance is used for 20 hours.

Answer 1

(500/1000)kW * 20h = 10kWh

Answer 2

First convert the power of the appliance from watts to kilowatts by dividing 500 watts by 1000
\[Power=\frac{500}{1000}=0.5\ kW\]
The energy (in kilowatt-hours) used in 20 hours operation is found by multiplying the power in kilowatts by the length of time:
\[Energy=0.5\times 20=10\ kilowatt-hours\]