# A microwave oven operates on 1500 W of power and is used for 20 minutes. How much electrical energy, in joules and kW•h, is used by the microwave oven?

Mar 22, 2018

$\text{1.8 MJ}$ and $\text{0.5 kWh}$

#### Explanation:

$\text{Power" = "Energy"/"Time}$

Unit of power is Watt.

$\text{1 W" = 1\ "J/s}$

$\text{E" = 1500\ "J"/cancel"s" × 20 cancel"min" × (60 cancel"s")/cancel"min" = "1800000 J" = "1.8 MJ}$

or

$\text{E" = "1500 W" × 20 cancel"min" × "1 h"/(60 cancel"min") = "500 Wh" = "0.5 kWh}$