A surprising discovery at TU Wien could help solve the riddle of high-temperature superconductivity: A famous "strange metal" turned out to be a superconductor.
Condensed Matter
Jul 21, 2021
0
22
In a classical second-order phase transition, condensed matter systems acquire long-range order upon cooling below the transition temperature, and the properties near the transition are driven by thermal fluctuations. These ...
Quantum Physics
Jun 14, 2021
0
8
Lancaster scientists have demonstrated that other physicists' recent "discovery" of the field effect in superconductors is nothing but hot electrons after all.
Condensed Matter
May 12, 2021
1
169
A recent series of experiments at the National High Magnetic Field Laboratory (National MagLab) at Los Alamos National Laboratory leveraged some of the nation's highest-powered nondestructive magnets to reveal an exotic new ...
General Physics
Apr 20, 2021
0
1745
As the worldwide demand for electronic devices continues to grow, so too does the strain on the finite resources used in their production, such as metals and fossil fuels. In an effort to provide renewable alternatives, researchers ...
Bio & Medicine
Apr 01, 2021
1
17
New measurements have solved a mystery in solid state physics: How is it that certain metals do not seem to adhere to the valid rules?
Materials Science
Mar 15, 2021
1
77
Superconductivity is a complete loss of electrical resistance. Superconductors are not merely very good metals: they represent a fundamentally different electronic state. In normal metals, electrons move individually, and ...
Superconductivity
Mar 15, 2021
0
179
Superconductivity—the ability of a material to transmit an electric current without loss—is a quantum effect that, despite years of research, is still limited to very low temperatures. Now a team of scientists at the ...
Superconductivity
Feb 05, 2021
3
3020
New photo-ferroelectric materials allow storage of information in a non-volatile way using light stimulus. The idea is to create energy efficient memory devices with high performance and versatility to face current challenges. ...
Optics & Photonics
Jan 20, 2021
0
237
Scientists at Tokyo Institute of Technology (Tokyo Tech) approach the two decade-old mystery of why an anomalous metallic state appears in the superconductor-insulator transition in 2-D superconductors. Through experimental ...
Quantum Physics
Dec 15, 2020
0
108
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:
where
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
