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ELECTRICAL ENERGY

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Electrical energy can refer to several closely related things. It can mean:

In any of these cases, the SI unit of electrical energy is the joule. The unit used by many electrical utility companies is the watt-hour (Wh) or the kilowatt-hour (kWh).

Contents

Energy stored in an electric field

The energy per unit volume of the electric field is:

\eta = \frac{1}{2} \epsilon |E|^2

where ε is the permittivity of the medium and E is the electric field vector.

Potential energy of a charged particle

Electrical energy is related to the position of an electric charge in an electric field. The electric potential energy of a charge Q situated at an electric potential V is equal to the product QV. The same expression gives the energy transformed when the charge moves through the potential difference V.

Energy of electricity

Electrical energy is the amount of work that can be done by electricity.

Usage note

Frequently, the terms electrical energy and electric power interchangeably. However, in physics, "energy" and "power" have different meanings. Power is energy per unit time. In other words, the phrases "flow of power," and "consume a quantity of electric power" are both incorrect and should be changed to "flow of energy" and "consume a quantity of electrical energy."

See also