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  2. Electric current - Wikipedia

    en.wikipedia.org/wiki/Electric_current

    The conventional symbol for current is I, which originates from the French phrase intensité du courant, (current intensity). [11] [12] Current intensity is often referred to simply as current. [13] The I symbol was used by André-Marie Ampère, after whom the unit of electric current is named, in formulating Ampère's force law (1820). [14]

  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. Henry (unit) - Wikipedia

    en.wikipedia.org/wiki/Henry_(unit)

    The henry (symbol: H) is the unit of electrical inductance in the International System of Units (SI). [1] If a current of 1 ampere flowing through a coil produces flux linkage of 1 weber turn, that coil has a self-inductance of 1 henry.‌ The unit is named after Joseph Henry (1797–1878), the American scientist who discovered electromagnetic induction independently of and at about the same ...

  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. 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.

  7. 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 ...

  8. Ammeter - Wikipedia

    en.wikipedia.org/wiki/Ammeter

    As the current through the coil increases, the plunger is drawn further into the coil and the pointer deflects to the right. An ammeter (abbreviation of ampere meter) is an instrument used to measure the current in a circuit. Electric currents are measured in amperes (A), hence the name. For direct measurement, the ammeter is connected in ...

  9. Electrical resistance and conductance - Wikipedia

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

    The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is electrical conductance, measuring the ease with which an electric current passes. Electrical resistance shares some conceptual parallels with mechanical friction. The SI unit of electrical resistance is the ohm (Ω ...