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Electrical resistivity (also called volume resistivity or specific electrical resistance) is a fundamental specific property of a material that measures its electrical resistance or how strongly it resists electric current. A low resistivity indicates a material that readily allows electric current.
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 ...
Sheet resistance is the resistance of a square piece of a thin material with contacts made to two opposite sides of the square. [1] It is usually a measurement of electrical resistance of thin films that are uniform in thickness.
If the resistance is not constant, the previous equation cannot be called Ohm's law, but it can still be used as a definition of static/DC resistance. [4] Ohm's law is an empirical relation which accurately describes the conductivity of the vast majority of electrically conductive materials over many orders of magnitude of current.
The values of the resistors are selected such that R 1 gives the highest load resistance, R 1 ||R 2 gives the nominal load resistance and either R 1 ||R 2 ||R 3 or R 2 ||R 3 gives the lowest load resistance. A voltmeter is then connected in parallel to the resistors and the measured values of voltage for each load state can be used to calculate ...
When calculating a Thévenin-equivalent voltage, the voltage divider principle is often useful, by declaring one terminal to be V out and the other terminal to be at the ground point. The Thévenin-equivalent resistance R Th is the resistance measured across points A and B "looking back" into the circuit. The resistance is measured after ...
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.
Simplified model for powering a load with resistance R L by a source with voltage V S and resistance R S.. The theorem was originally misunderstood (notably by Joule [4]) to imply that a system consisting of an electric motor driven by a battery could not be more than 50% efficient, since the power dissipated as heat in the battery would always be equal to the power delivered to the motor when ...