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Various resistor types of different shapes and sizes. A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses.
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 ...
Similarly, the rate of flow of electrical charge, that is, the electric current, through an electrical resistor is proportional to the difference in voltage measured across the resistor. More generally, the hydraulic head may be taken as the analog of voltage, and Ohm's law is then analogous to Darcy's law which relates hydraulic head to the ...
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.
Faraday was the first to publish the results of his experiments. [5] [6] Faraday's 1831 demonstration [7] Faraday's notebook on August 29, 1831 [8] describes an experimental demonstration of electromagnetic induction (see figure) [9] that wraps two wires around opposite sides of an iron ring (like a modern toroidal transformer).
In the figure, R x is the fixed, yet unknown, resistance to be measured. R 1, R 2, and R 3 are resistors of known resistance and the resistance of R 2 is adjustable. The resistance R 2 is adjusted until the bridge is "balanced" and no current flows through the galvanometer V g.
A metre bridge is a simple type of potentiometer which may be used in school science laboratories to demonstrate the principle of resistance measurement by potentiometric means. A resistance wire is laid along the length of a metre rule and contact with the wire is made through a galvanometer by a slider. When the galvanometer reads zero, the ...
If a contact patch is sufficiently small, with dimensions comparable or smaller than the mean free path of electrons resistance at the patch can be described by the Sharvin mechanism, whereby electron transport can be described by ballistic conduction. Generally, over time, contact patches expand and the contact resistance at an interface ...