Electrical energy
Electrical energy or electromagnetic energy is a form of energy present in any electric field or magnetic field, or in any volume containing electromagnetic radiation. The SI unit of electrical energy is the joule, while the unit used by electrical utility companies is the watt-hour (W·h) or the kilowatt-hour (kW·h).
Electrical energy is related to the position of an electric charge in an electric field. The electrical energy of a charge Q situated at the electric potential V equals to the product QV. If V is a potential difference, the same expression gives the energy transformed when the charge moves through the potential difference. The electrical energy is the integral of the power over time:
p(t) is the instantaneous power, v(t) is the voltage over time, and i(t) is the current over time. For DC, this simplifies to:
Electrical energy is also identical to the electromagnetic fields surrounding a transmission line, the fields contained in capacitors and inductors, or the fields propagating in space as electromagnetic radiation. The amount of electrical energy surrounding a conductor or travelling through a waveguide may be calculated by integrating the cross product of the magnetic and electric field vectors throughout the volume. (And the reason that Power equals Volts times Current is directly related to the fact that electromagnetic energy flow equals e-field times b-field.)
The name of the topic covering production, distribution, and use of electrical energy is electric power. The term Electric Power is frequently misused as an alternate name for electrical energy. Yet energy and power are two different things. In other words, the phrase "flow of power," and the phrase "consume a quantity of electric power" are both incorrect and should be changed to "flow of energy" and "consume a quantity of electrical energy", respectively.
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