It can also be carried by ions in an electrolyte or by both ions and electrons in a plasma The SI unit for measuring the rate of flow of electric charge is the ampere, which is charge flowing through some surface at the rate of one coulomb per second. Electric current is measured using an ammeter
The conventional symbol for current is «I» . Electric current is defined to flow in the same direction as positive charges. In metals where the charge carriers (electrons) are negative, conventional current flows in the opposite direction as the electrons.
§ A flow of positive charges gives the same electric current as a flow of negative charges in the opposite direction § In metals, which make up the wires and other conductors in most electrical circuits, the positive charges are immobile, and only the negatively charged electrons flow
Alternating current § AC is the form in which electric power is delivered to businesses and residences § The frequency of the electrical system varies by country; most electric power is generated at either 50 or 60 Hertz. Some countries have a mixture of 50 Hz and 60 Hz supplies, notably Japan. § The abbreviations AC and DC are often used to mean simply alternating and direct, as when they modify current or voltage § The earliest recorded practical application of alternating current is by Guillaume Duchenne, inventor and developer of electrotherapy in 1855. § In alternating current (AC or ac) the movement of electric charge periodically reverses direction. In direct current (DC), the flow of electric charge is only in one direction.
Direct current § Direct current (DC) is the unidirectional flow of electric charge § Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams.
Used books and materials: 1. 1) V. B. Grigorov tutorial publication. 2. 2) Site www. en. wikipedia. org 3. 3) Site www. en. academic. ru Execute work Spitsin Vladislav Specialty 160901 2 -nd course Irkutsk 2011
