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  2. Electric current - Wikipedia

    en.wikipedia.org/wiki/Electric_current

    Electrons are the charge carriers in most metals and they follow an erratic path, bouncing from atom to atom, but generally drifting in the opposite direction of the electric field. The speed they drift at can be calculated from the equation: where. is the drift velocity. is the electric current.

  3. Ampere - Wikipedia

    en.wikipedia.org/wiki/Ampere

    The ampere (/ ˈæmpɛər / AM-pair, US: / ˈæmpɪər / AM-peer; [1][2][3] symbol: A), [4] often shortened to amp, [5] is the unit of electric current in the International System of Units (SI). One ampere is equal to 1 coulomb (C) moving past a point per second. [6][7][8] It is named after French mathematician and physicist André-Marie ...

  4. Ampère's circuital law - Wikipedia

    en.wikipedia.org/wiki/Ampère's_circuital_law

    Ampère's original circuital law. In 1820 Danish physicist Hans Christian Ørsted discovered that an electric current creates a magnetic field around it, when he noticed that the needle of a compass next to a wire carrying current turned so that the needle was perpendicular to the wire. [6][7] He investigated and discovered the rules which ...

  5. Ohm's law - Wikipedia

    en.wikipedia.org/wiki/Ohm's_law

    Ohm's law states that the electric current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, [ 1 ] one arrives at the three mathematical equations used to describe this relationship: [ 2 ] where I is the current through the conductor ...

  6. Current density - Wikipedia

    en.wikipedia.org/wiki/Current_density

    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.

  7. Coulomb - Wikipedia

    en.wikipedia.org/wiki/Coulomb

    The coulomb (symbol: C) is the unit of electric charge in the International System of Units (SI). [1][2] It is equal to the electric charge delivered by a 1 ampere current in 1 second and is defined in terms of the elementary charge e, at about 6.241 509 × 1018 e. [2][1]

  8. Electrical resistance and conductance - Wikipedia

    en.wikipedia.org/wiki/Electrical_resistance_and...

    Also called chordal or DC resistance This corresponds to the usual definition of resistance; the voltage divided by the current R s t a t i c = V I. {\displaystyle R_{\mathrm {static} }={V \over I}.} It is the slope of the line (chord) from the origin through the point on the curve. Static resistance determines the power dissipation in an electrical component. Points on the current–voltage ...

  9. Volt-ampere - Wikipedia

    en.wikipedia.org/wiki/Volt-ampere

    1 kg⋅m 2 ⋅s −3. The volt-ampere (SI symbol: VA, [1] sometimes V⋅A or V A) is the unit of measurement for apparent power in an electrical circuit. It is the product of the root mean square voltage (in volts) and the root mean square current (in amperes). [2] Volt-amperes are usually used for analyzing alternating current (AC) circuits.