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 (Wh) or the kilowatt-hour (kWh.)
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 potentialV 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.
Electrical energy is also identical to the electromagnetic fields surrounding a transmission line, contained in capacitors and inductors, or propagating in space as electromagnetic radiation. The quantity 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.
The topic regarding the production, distribution, and use of electrical energy is called electric power, and this term is frequently used as an inaccurate name for electrical energy. In other words, the phrases "flow of power" and "consume a quantity of electric power" are incorrect, and should be changed to "flow of energy" and "consume a quantity of electrical energy", respectively.
The electromagnetic spectrum, shown in the table, extends from frequencies used in the electric power grid (at the long-wavelength end) to gamma radiation (at the short-wavelength end), covering wavelengths from thousands of kilometres down to fractions of the size of an atom, though in principle the spectrum is actually infinite.
Electromagnetic spectroscopy is the branch of physics that deals with the characterization of matter by its spectra.
At zero frequency the energy is emitted by batteries and DC power supplies, while at 50 Hz and 60 Hz it is produced by rotary magnetic generators and ducted through the international power grids.
Electromagnetic fields are present everywhere but are invisible to the human eye.
In the electromagnetic spectrum, gamma rays given off by radioactive materials, cosmic rays and X-rays carry this property and are called 'ionizing radiation'.
Man-made sources of electromagnetic fields that form a major part of industrialized life - electricity, microwaves and radiofrequency fields are found at the relatively long wavelength and low frequency end of the electromagnetic spectrum and their quanta are thought to be unable to break chemical bonds.
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