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An electricity meter, electric meter, electrical meter, energy meter, or kilowatt-hour meter is a device that measures the amount of electric energy consumed by a residence, a business, or an electrically powered device over a time interval. Electric utilities use electric meters installed at customers' premises for billing and monitoring purposes.
astro: power per square meter received from Proxima Centauri, the closest star known 10 −10: 1 × 10 −10: −68 dBm astro: estimated total Hawking radiation power of all black holes in the observable universe. [7] [8] [9] 1.5 × 10 −10: −68 dBm biomed: power entering a human eye from a 100-watt lamp 1 km away 10 −9: nano-(nW) 2–15 ...
Electricity is usually sold by the kilowatt hour (3.6 MJ) which is the product of power in kilowatts multiplied by running time in hours. Electric utilities measure power using electricity meters, which keep a running total of the electric energy delivered to a customer.
Electric power is the rate of transfer of electrical energy within a circuit.Its SI unit is the watt, the general unit of power, defined as one joule per second.Standard prefixes apply to watts as with other SI units: thousands, millions and billions of watts are called kilowatts, megawatts and gigawatts respectively.
For example, when a light bulb with a power rating of 100 W is turned on for one hour, the energy used is 100 watt hours (W·h), 0.1 kilowatt hour, or 360 kJ. This same amount of energy would light a 40-watt bulb for 2.5 hours, or a 50-watt bulb for 2 hours.
If a laptop computer in sleep mode consumes 5 W, the meter may read anything from 0 to 15.25 W, without taking into account errors due to non-sinusoidal waveform. In practice accuracy can be improved by connecting a fixed load such as an incandescent light bulb, adding the device in standby, and using the difference in power consumption. [ 3 ]
A kilowatt-hour is a unit of energy. Kilowatt per hour would be a rate of change of power flow with time. Work is the amount of energy transferred to a system; power is the rate of delivery of energy. Energy is measured in joules, or watt-seconds. Power is measured in watts, or joules per second. For example, a battery stores energy.
A unit of electrical energy, particularly for utility bills, is the kilowatt-hour (kWh); [3] one kilowatt-hour is equivalent to 3.6 megajoules. Electricity usage is often given in units of kilowatt-hours per year or other periods. [4] This is a measurement of average power consumption, meaning the average rate at which energy is transferred ...