The energy company does not bill you in joules, the numbers would be enormous. It uses a bigger, friendlier unit, the kilowatt-hour, and the cost is just that number of units times a price.
The kilowatt-hour is the energy used by a one kilowatt appliance in one hour. Energy in kilowatt-hours is power in kilowatts multiplied by time in hours, and the cost is that energy multiplied by the price of one kilowatt-hour.
The kilowatt-hour (kWh) is the energy transferred by a 1 kW appliance in 1 hour. It is the unit of energy used on an electricity bill.
cost = energy in kWh × price per kWh. The kilowatt-hour is a unit of energy, not power.
Set an appliance power and running time and watch the kilowatt-hours and the cost add up.
Four quick checks. Each correct answer earns XP and lights this skill on your star map.
The kilowatt-hour is a unit of...
Energy in kilowatt-hours is...
The cost of the electricity used is...
A 1 kW appliance running for 1 hour uses...
Work out the energy in kilowatt-hours first, then multiply by the price.
A 2.0 kW heater runs for 3.0 hours. Electricity costs 30 cents per kWh. Find the cost.
The kilowatt-hour is a unit of energy, not power. Use the power in kilowatts and the time in hours, then multiply the kilowatt-hours by the price per unit to get the cost.
Unlocks once the four checks above are done. Worth more XP, written in the style of Paper 2.
A 2.0 kW heater runs for 3.0 hours. The energy it uses is...
At 30 cents per kWh, the cost of using 6.0 kWh is...
A 100 W lamp is left on for 10 hours. The energy it uses is...
Kilowatt-hours and cost complete the electrical quantities strand. Keep the chain going.