Researchers dynamically tune friction in graphene

The friction on a graphene surface can be dynamically tuned using external electric fields, according to researchers at the University of Illinois Urbana-Champaign led by Professor Rosa Espinosa-Marzal of the Department of ...

How hydrophobicity shapes protein assemblies

Through a nuanced balance of electrical and hydrophobic forces, biological molecules self-assemble into the large functional structures that maintain life's vital functions. Understanding how proteins self-assemble requires ...

Searching for dark matter with the world's most sensitive radio

Since the 1960s there has been plenty of evidence to support the existence of dark matter through astrophysical and cosmological observations, and at this point we're very confident that it exists. The question remains, though: ...

Quantum question about the anomalous Hall effect answered

A mysterious magnetic effect that causes the path that electrons take through a material to bend—called the anomalous Hall effect—has been elucidated in a new mathematical analysis by two RIKEN physicists. Their work ...

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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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