(PhysOrg.com) -- Physicists at Yale University have made the first definitive measurements of "persistent current," a small but perpetual electric current that flows naturally through tiny rings of metal wire even without ...
General Physics
Oct 8, 2009
16
0
One hundred years ago today, on May 29, 1919, measurements of a solar eclipse offered verification for Einstein's theory of general relativity. Even before that, Einstein had developed the theory of special relativity, which ...
General Physics
May 31, 2019
25
3962
Even if you don't know it by name, everyone is familiar with Newton's third law, which states that for every action, there is an equal and opposite reaction. This idea can be seen in many everyday situations, such as when ...
Radio waves, microwaves and even light itself are all made of electric and magnetic fields. The classical theory of electromagnetism was completed in the 1860s by James Clerk Maxwell. At the time, Maxwell's theory was revolutionary, ...
General Physics
Apr 11, 2017
72
6578
Quantum engineers from UNSW Sydney have removed a major obstacle that has stood in the way of quantum computers becoming a reality. They discovered a new technique they say will be capable of controlling millions of spin ...
Quantum Physics
Aug 13, 2021
1
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Semiconductors are the basic building blocks of digital devices. Improvements in semiconductor functionality and performance are likewise enabling next-generation applications of semiconductors for computing, sensing and ...
Condensed Matter
Oct 11, 2019
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Information in computers is transmitted through semiconductors by the movement of electrons and stored in the direction of the electron spin in magnetic materials. To shrink devices while improving their performance—a goal ...
Quantum Physics
May 20, 2022
2
620
When it comes to graphene, it appears that superconductivity runs in the family.
Superconductivity
Jul 8, 2022
2
1956
Deep within Earth, swirling liquid iron generates our planet's protective magnetic field. This magnetic field is invisible but is vital for life on Earth's surface: it shields the planet from harmful solar wind and cosmic ...
Earth Sciences
Jan 20, 2020
11
2083
Since the discovery of graphene more than 15 years ago, researchers have been in a global race to unlock its unique properties. Not only is graphene—a one-atom-thick sheet of carbon arranged in a hexagonal lattice—the ...
Nanomaterials
Oct 12, 2020
1
6703
In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. This electric field exerts a force on other electrically charged objects. The concept of an electric field was introduced by Michael Faraday.
The electric field is a vector field with SI units of newtons per coulomb (N C−1) or, equivalently, volts per metre (V m−1). The SI base units of the electric field are kg·m·s−3·A−1. The strength of the field at a given point is defined as the force that would be exerted on a positive test charge of +1 coulomb placed at that point; the direction of the field is given by the direction of that force. Electric fields contain electrical energy with energy density proportional to the square of the field intensity. The electric field is to charge as gravitational acceleration is to mass and force density is to volume.
A moving charge has not just an electric field but also a magnetic field, and in general the electric and magnetic fields are not completely separate phenomena; what one observer perceives as an electric field, another observer in a different frame of reference perceives as a mixture of electric and magnetic fields. For this reason, one speaks of "electromagnetism" or "electromagnetic fields." In quantum mechanics, disturbances in the electromagnetic fields are called photons, and the energy of photons is quantized.
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