Part of the Electronics glossary: Also see voltage, resistance, and Ohm's Law. Current is a flow of electrical charge carriers, usually electrons or electron-deficient atoms. common symbol for current is the uppercase letter I. unit is the ampere, symbolized by A. One ampere of current represents one coulomb of electrical charge (6.24 x 1018 charge carriers) moving past a specific point in one second. Physicists consider current to flow from relatively positive points to relatively negative points; this is called conventional current or Franklin current. Electrons, the most common charge carriers, are negatively charged. from relatively negative points to relatively positive points. Electric current can be either direct or alternating. Direct current (DC) flows in the same direction at all points in time, although the instantaneous magnitude of the current might vary. In an alternating current (AC), the charge carriers reverses direction periodically.

complete AC cycles per second is the frequency, which is measured in hertz. example of pure DC is the current produced by an electrochemical cell. The output of a power-supply rectifier, prior to filtering, is an example of pulsating DC. The output of common utility outlets is AC. Current per unit cross-sectional area is known asIt is expressed in amperes per square meter, amperes per square centimeter, or amperes perCurrent density can also be expressed in amperesIn general, the greater the current in a conductor, the higher the current density. However, in some situations, current density varies in different parts ofA classic example is the so-called skin effect, in which current density is high near the outer surface of a conductor, and low near the center. This effect occurs with alternating currents at high frequencies. Another example is the current inside an active electronic component such as a field-effect transistor (FET). An electric current always produces a magnetic field.

The stronger the current, the more intense the magnetic field. A pulsating DC, or an AC, characteristically produces an electromagneticThis is the principle by which wireless signal propagation occurs. Posted by: Margaret RouseDivision G Stars and Stellar Physics Christopher Simon JefferyArmagh ObservatoryCollege HillArmagh BT61 9DGUnited KingdomPhone: +44 283 752 2928Fax: +44 283 752 7174Email 1: csjarmacukEmail 2: csjstararmacukPersonal website: star.arm.ac.uk/~csj/Organization website: http://star.arm.ac.ukLast updated:July 25, 2016 Jaymie MatthewsUniversity of British ColumbiaDept of Physics and AstronomyHennings Bldg6224 Agricultural RdVancouver BC V6T 1Z1British Columbia (BC)CanadaPhone: +1 604 822 2696Fax: +1 250 822 5324Email 1: matthewsastroubccaEmail 2: matthewsphasubccaOrganization website: http://www.phas.ubc.ca/Last updated:July 25, 2016 Saskia HekkerMax Planck Institute for Solar System ResearchJustus von Liebigweg 337077 GöttingenGermanyPhone: +49 (0)551 384 979 264Email: HekkermpsmpgdeOrganization website: http://www.mps.mpg.de/3163012/Das-Alter-von-SternenLast updated:May 24, 2016

Christopher Simon Jeffery (President) Product Description Sit back, relax, and let your stress and tension melt away. This relaxing massager is uniquely styled as a decorative throw pillow, but place it behind you, and the magic begins. As you lean back, a pressure activated switch will turn on this pillow automatically. When you get up, it turns itself back off, so you never need to worry about wasting batteries, or leaving it running when not in use. ac unit for airstreamIt is not your average vibrating pillow, and features a pulsating motor for a more beneficial treatment. air conditioner split system wikiRegular style pillows will simply shake at the same speed, so your muscles are able to get used to it quickly. window ac unit freonThis one also vibrates as the massage method, but the speed and intensity will change as it runs to provide a better effect.

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