Power

The power of a device is how quickly it transfers electrical energy. How much energy it transfers every second.

A more powerful device will transfer more energy every second. A kettle, for example, transfers electrical energy into heat energy. A more powerful kettle will boil the same amount of water quicker or boil more water in the same time.

Energy is measured in Joules. Power could be measured in Joules per second but we usually measure it in watts (W) or kilowatts (kW)

Power = 0.5 kW	Power = 2.5 kW	Power = 5kW	Power = 20kW
This little water heater is used to make single cups of tea.	For a few cups of tea at home this does the job nicely.	One of these in the staff room will make lots of cups of tea.	This boiler heats the water for a swimming pool.