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Science Concept: Paying for Power

Your local utility company sends your household a bill for the electricity and/or natural gas you use.

For electricity, you pay for the kilowatt-hours (kWh) used in your home during the billing period. What is a kWh? It is equal to 1,000 watts of electricity used for one hour. If you leave fifty 20-watt light bulbs on for an hour, you’ve used one kWh of electricity.

For natural gas, you pay for the therms you’ve used during the billing period. What is a therm? It is the number of cubic feet (cu. ft.) of natural gas used, multiplied by a therm factor. The therm factor is based on the energy content of the gas, which can vary. Some utilities simply assume an average therm factor.