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The siemens (symbol: S) is the unit of electric conductance, electric susceptance, and electric admittance in the International System of Units (SI). Conductance, susceptance, and admittance are the reciprocals of resistance, reactance, and impedance respectively; hence one siemens is equal to the reciprocal of one ohm (Ω −1) and is also referred to as the mho.
In a superconductor, the resistance drops abruptly to zero when the material is cooled below its critical temperature. In a normal conductor, the current is driven by a voltage gradient, whereas in a superconductor, there is no voltage gradient and the current is instead related to the phase gradient of the superconducting order parameter. [15]
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 ...
Admittance Y, measured in siemens, is defined as the inverse of impedance Z, measured in ohms: Resistance is a measure of the opposition of a circuit to the flow of a steady current, while impedance takes into account not only the resistance but also dynamic effects (known as reactance). Likewise, admittance is not only a measure of the ease ...
The formula is a combination of Ohm's law and Joule's law: = = =, where P is the power, R is the resistance, V is the voltage across the resistor, and I is the current through the resistor. A linear resistor has a constant resistance value over all applied voltages or currents; many practical resistors are linear over a useful range of currents.
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 −3 ⋅A −2: ρ resistivity: ohm ...
The unvarying current which, when passed through a solution of silver nitrate in water, deposits silver at the rate of 0.001 118 00 grams per second The current produced in a conductor with a 1 ohm resistance when there is a potential difference of 1 volt between its ends 0.1 CGS-EMU units of electric current international ohm
Measure for how easily current flows through a material siemens (S = Ω −1) L −2 M −1 T 3 I 2: scalar Electrical conductivity: σ: Measure of a material's ability to conduct an electric current S/m L −3 M −1 T 3 I 2: scalar Electric potential: φ: Energy required to move a unit charge through an electric field from a reference point ...