electric+current

This i from me Dhafer for everyone in 4Victorious:].This is the information about heat.I copied it from this website.this is the shortcut **[]** **Electric current** means, depending on the context, a flow of [|electric charge] (a [|phenomenon]) or the rate of flow of electric charge (a [|quantity]).[|[1]] This flowing electric charge is typically carried by moving [|electrons], in a [|conductor] such as [|wire]; in an [|electrolyte], it is instead carried by [|ions], and, in a [|plasma], by both.[|[2]] The [|SI] unit for measuring the rate of flow of electric charge is the [|ampere]. Electric current is measured using an [|ammeter]

Metals
A [|solid] [|conductive] metal contains mobile, or [|free, electrons]. These electrons are bound to the [|metal lattice] but not to any individual atom. Even with no external [|electric field] applied, these electrons move about randomly due to [|thermal energy] but, on average, there is zero net current within the metal. Given a plane through which the wire passes, the number of [|electrons] moving from one side to the other in any period of time is on average equal to the number passing in the opposite direction. As [|George Gamow] put in his science-popularizing book, //One, Two, Three...Infinity// (1947), "The metallic substances differ from all other materials by the fact that the outer shells of their atoms are bound rather loosely, and often let one of their electrons go free. Thus the interior of a metal is filled up with a large number of unattached electrons that travel aimlessly around like a crowd of displaced persons. When a metal wire is subjected to electric force applied on its opposite ends, these free electrons rush in the direction of the force, thus forming what we call an electric current." A typical wire for electrical conduction is the stranded [|copper] [|wire]. When a metal wire is connected across the two terminals of a [|DC] [|voltage source] such as a [|battery], the source places an electric field across the conductor. The moment contact is made, the [|free electrons] of the conductor are forced to drift toward the [|positive] terminal under the influence of this field. The free electrons are therefore the [|current carrier] in a typical solid conductor. For an electric current of 1 ampere, 1 [|coulomb] of [|electric charge] (which consists of about 6.242 × 1018 [|elementary charges]) drifts every [|second] through any plane through which the conductor passes. For a steady flow, the current //I// in [|amperes] can be calculated with the following equation: where //Q// is the [|electric charge] in [|coulombs] transferred, and //t// is the [|time] in [|seconds] More generally, electric current can be represented as the time rate of change of charge, or

[[|edit]] Other med
In metallic solids, electricity flows by means of electrons, from higher to lower [|electrical potential]. In other media, any stream of charged objects may constitute an electric current. So when there is higher cross sectional area there is less resistance. Conventional currents flows in the opposite way of electron current. In terms of Ohm's law current is proportional to voltage and inversely proportional to the resistance. In a [|vacuum], a beam of [|ions] or electrons may be formed. In other conductive materials, the electric current is due to the flow of both positively and negatively charged particles at the same time. In still others, the current is entirely due to [|positive charge flow]. For example, the electric currents in [|electrolytes] are flows of electrically charged atoms ([|ions]), which exist in both positive and negative varieties. In a common lead-acid [|electrochemical] cell, electric currents are composed of positive hydrogen ions (protons) flowing in one direction, and negative sulfate ions flowing in the other. Electric currents in sparks or [|plasma] are flows of electrons as well as positive and negative ions. In ice and in certain solid electrolytes, the electric current is entirely composed of flowing [|ions]. In a [|semiconductor] it is sometimes useful to think of the current as due to the flow of positive "[|holes]" (the mobile positive charge carriers that are places where the semiconductor crystal is missing a valence electron). This is the case in a p-type