Quantum sensor can detect electromagnetic signals of any frequency

Quantum sensors, which detect the most minute variations in magnetic or electrical fields, have enabled precision measurements in materials science and fundamental physics. But these sensors have only been capable of detecting ...

Single-molecule optoelectronic devices

Single-molecule electronic devices, which use single molecules or molecular monolayers as their conductive channels, offer a new strategy to resolve the miniaturization and functionalization bottlenecks encountered by traditional ...

Tunable quantum traps for excitons

Researchers at ETH Zurich have succeeded for the first time in trapping excitons—quasiparticles consisting of negatively charged electrons and positively charged holes—in a semiconductor material using controllable electric ...

Custom 'headphones' boost atomic radio reception 100-fold

Researchers at the National Institute of Standards and Technology (NIST) have boosted the sensitivity of their atomic radio receiver a hundredfold by enclosing a small glass cylinder of cesium atoms inside what looks like ...

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Electric field

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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