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The ampere is an SI base unit and electric current is a base quantity in the International System of Quantities (ISQ). [4]: 15 Electric current is also known as amperage and is measured using a device called an ammeter. [2]: 788 Electric currents create magnetic fields, which are used in motors, generators, inductors, and transformers.
In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. [1] The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional area at a given point in space, its direction being that of the motion of the positive charges at this point.
The net current into a volume is = where S = ∂V is the boundary of V oriented by outward-pointing normals, and dS is shorthand for NdS, the outward pointing normal of the boundary ∂V. Here J is the current density (charge per unit area per unit time) at the surface of the volume. The vector points in the direction of the current.
electric charge: coulomb: C A⋅s I electric current: ampere: A = C/s = W/V A J electric current density: ampere per square metre A/m 2: A⋅m −2: U, ΔV; Δϕ; E, ξ potential difference; voltage; electromotive force: volt: V = J/C kg⋅m 2 ⋅s −3 ⋅A −1: R; Z; X electric resistance; impedance; reactance: ohm: Ω = V/A kg⋅m 2 ⋅s ...
The branch of physics that studies electrical charges and electrical currents. electrolyte A liquid or solid medium that carries electric current in the form of ions. electromagnet A magnet that generates a magnetic field from an electric current. electromagnetic compatibility The control of unwanted electromagnetic interference ...
This means that the direction of the back EMF of an induced field opposes the changing current that is its cause. D.J. Griffiths summarized it as follows: Nature abhors a change in flux. [7] If a change in the magnetic field of current i 1 induces another electric current, i 2, the direction of i 2 is opposite that of the change in i 1.
In condensed matter physics and electrochemistry, drift current is the electric current, or movement of charge carriers, which is due to the applied electric field, often stated as the electromotive force over a given distance. When an electric field is applied across a semiconductor material, a current is produced due to the flow of charge ...
A salt bridge or porous membrane connects the two solutions, keeping electric neutrality and the avoidance of charge accumulation. The metal's differences in oxidation/reduction potential drive the reaction until equilibrium. [1] Key features: spontaneous reaction; generates electric current; current flows through a wire, and ions flow through ...