Related topics: magnetic field ยท superconductors

Examining domain walls in magnetic nanowires

Magnetic domains walls are known to be a source of electrical resistance due to the difficulty for transport electron spins to follow their magnetic texture. This phenomenon holds potential for utilization in spintronic devices, ...

Building better superconductors with palladium

It is one of the most exciting races in modern physics: How can we produce the best superconductors that remain superconducting even at the highest possible temperatures and ambient pressure? In recent years, a new era of ...

The quantum spin liquid that isn't one

For two decades, it was believed that a possible quantum spin liquid was discovered in a synthetically produced material. In this case, it would not follow the laws of classical physics even on a macroscopic level, but rather ...

Closing in on next-generation atom-thick photonic devices

From microscopes and cameras to night vision devices and optical fiber communications, photodetectors have a wide array of applications. Photodetectors capture and convert light into electrical signals but are often limited ...

page 1 from 22

Electrical resistance

The electrical resistance of an object is a measure of its opposition to the passage of a steady electric current. An object of uniform cross section will have a resistance proportional to its length and inversely proportional to its cross-sectional area, and proportional to the resistivity of the material.

Discovered by Georg Ohm in the late 1820s, electrical resistance shares some conceptual parallels with the mechanical notion of friction. The SI unit of electrical resistance is the ohm, symbol Ω. Resistance's reciprocal quantity is electrical conductance measured in siemens, symbol S.

The resistance of a resistive object determines the amount of current through the object for a given potential difference across the object, in accordance with Ohm's law:


For a wide variety of materials and conditions, the electrical resistance does not depend on the amount of current through or the amount of voltage across the object, meaning that the resistance R is constant for the given temperature. Therefore, the resistance of an object can be defined as the ratio of voltage to current:

In the case of nonlinear objects (not purely resistive, or not obeying Ohm's law), this ratio can change as current or voltage changes; the ratio taken at any particular point, the inverse slope of a chord to an I–V curve, is sometimes referred to as a "chordal resistance" or "static resistance".

This text uses material from Wikipedia, licensed under CC BY-SA