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"Breaks down structure of matter into atoms and, by use of conventional symbols, shows the action of electrons within an atom. The principles involved in the flow of current are explained and a volt, ampere and Ohm are defined."
Originally a public domain film from the Library of Congress Prelinger Archives, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.
The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).
Wikipedia license: http://creativecommons.org/licenses/by-sa/3.0/
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire. In addition, electricity encompasses less familiar concepts such as the electromagnetic field and electromagnetic induction.
The word is from the New Latin ēlectricus, "amber-like", coined in the year 1600 from the Greek ήλεκτρον (electron) meaning amber, because electrical effects were produced classically by rubbing amber.
In general usage, the word "electricity" adequately refers to a number of physical effects. In a scientific context, however, the term is vague, and these related, but distinct, concepts are better identified by more precise terms:
Electric charge: a property of some subatomic particles, which determines their electromagnetic interactions. Electrically charged matter is influenced by, and produces, electromagnetic fields.
Electric current: a movement or flow of electrically charged particles, typically measured in amperes.
Electric field: an influence produced by an electric charge on other charges in its vicinity.
Electric potential: the capacity of an electric field to do work on an electric charge, typically measured in volts.
Electromagnetism: a fundamental interaction between the magnetic field and the presence and motion of an electric charge.
The most common use of the word "electricity" is less precise. It refers to:
Electric power (which can refer imprecisely to a quantity of electrical potential energy or else more correctly to electrical energy per time) that is provided commercially, by the electrical power industry...
Electrical phenomena have been studied since antiquity, though advances in the science were not made until the seventeenth and eighteenth centuries. Practical applications for electricity however remained few, and it would not be until the late nineteenth century that engineers were able to put it to industrial and residential use. The rapid expansion in electrical technology at this time transformed industry and society. Electricity's extraordinary versatility as a source of energy means it can be put to an almost limitless set of applications which include transport, heating, lighting, communications, and computation. Electrical power is the backbone of modern industrial society, and is expected to remain so for the foreseeable future...
The movement of electric charge is known as an electric current, the intensity of which is usually measured in amperes. Current can consist of any moving charged particles; most commonly these are electrons, but any charge in motion constitutes a current.
By historical convention, a positive current is defined as having the same direction of flow as any positive charge it contains, or to flow from the most positive part of a circuit to the most negative part. Current defined in this manner is called conventional current. The motion of negatively charged electrons around an electric circuit, one of the most familiar forms of current, is thus deemed positive in the opposite direction to that of the electrons. However, depending on the conditions, an electric current can consist of a flow of charged particles in either direction, or even in both directions at once. The positive-to-negative convention is widely used to simplify this situation.
The process by which electric current passes through a material is termed electrical conduction... While the particles themselves can move quite slowly, sometimes with an average drift velocity only fractions of a millimetre per second, the electric field that drives them itself propagates at close to the speed of light, enabling electrical signals to pass rapidly along wires.