Current - Vernazio Stewart

(Topic Description -

What is Current?

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By MM Del Rosario

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An ammeter is a measuring instrument used to measure the electric current in a circuit.

What is Current?

An electric current is produced when electrons move through a substance. Cooper wire is often used to carry electrical current. Electrons normally revolve about the nucleus of each atom of cooper in the wire, but when electrical pressure ( that is the voltage) from a battery or generator is applied, some of these electrons are forced out of their orbits and pass from atom to atom along the length of the wire. These electrons are called free electrons and come from the outer orbit of the atom.

History of Current

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 thatengineers 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.[1]

Application of Current

  • A direct current (DC) is produced when free electrons move in only one direction in a conductor.
  • Pulsating direct current is a current in one direction which regularly varies in intensity.
  • Alternating Current (AC) is produced when the current regularly changes its direction and intensity.

Direction of Current Flow

The voltage produced by a DC source causes electrons to flow through a circuit from one terminal of the source to the other. It was once thought that the current flow was from the positive terminal to the negative terminal. This is referred to as conventional current flow. Although it was later discovered that the current actually flows in the other direction, this conventional current flow is still used today.


  1. Beiser, Arthur. Schaum's Outline of Theory and Problems of Physical Science. New York [etc.: McGraw-Hill Book, 1988. Print.
  2. ("Electricity." Wikipedia, the Free Encyclopedia. Web. 09 Aug. 2011. <>
  3. (Ref #3 - from book, library, journal)

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