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The wattmeter is an instrument for measuring the electric active power (or the average of the rate of flow of electrical energy) in watts of any given circuit. Electromagnetic wattmeters are used for measurement of utility frequency and audio frequency power; other types are required for radio frequency measurements.
A multimeter (also known as a volt-ohm-milliammeter, volt-ohmmeter or VOM) [1] is a measuring instrument that can measure multiple electrical properties. [ 2 ] [ 3 ] A typical multimeter can measure voltage , resistance , and current , [ 4 ] in which case can be used as a voltmeter , ohmmeter , and ammeter .
Measurement of electrical quantities may be done to measure electrical parameters of a system. Using transducers , physical properties such as temperature, pressure, flow, force, and many others can be converted into electrical signals, which can then be conveniently measured and recorded.
North American domestic analog (Ferraris disk) electricity meter. Electricity meter with transparent plastic case (Israel) 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.
This same amount of energy would light a 40-watt bulb for 2.5 hours, or a 50-watt bulb for 2 hours. Power stations are rated using units of power, typically megawatts or gigawatts (for example, the Three Gorges Dam in China is rated at approximately 22 gigawatts). This reflects the maximum power output it can achieve at any point in time.
Each pairing of a current measuring unit plus a potential measuring unit is then termed a stator or element. Thus, for example, a meter for a four wire service will include three elements. Blondel's Theorem simplifies the work of an electrical utility worker by specifying that an N wire service will be correctly measured by a N-1 element meter.
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 ...
The Tweet-a-watt [13] is a hacked version of the standard Kill-A-Watt Plug in Power Meter. By piggybacking on the device's on-board LM2902N op-amp chip, the creator was able to get readings for voltage and current and transmit to a computer, which then sent this to Twitter via handle @tweetawatt. [ 14 ]