The Cost of Electricity

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Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!

The of an appliance is the at which it uses electrical energy. Power is measured in (W), where 1W = 1 J/s. More powerful appliances may be measured in kilowatts, where 1 kW = W.

When we buy electricity, we buy it in units called (kWh). Sometimes it is simply called a unit. The formula is:

kilowatt hours used = power in × time in

To work out the cost, we have to multiply the kilowatt hours by the .

Example:
If electricity costs 9 p per unit, the cost of running a 2 kW fire for 2 hours is [?] p.

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