Intelligent metamaterials behave like electrostatic chameleons

A chameleon can flexibly change its colour to match its surroundings. And a similar phenomenon can now be seen in a new class of smart materials called metamaterials. The trouble is that these metamaterials lack the ability ...

Study shows way to design 'digital' metamaterials

Metamaterials, precisely designed composite materials that have properties not found in natural ones, could be used to make light-bending invisibility cloaks, flat lenses and other otherwise impossible devices.

New capacitors to improve electric vehicles

Scientists from the National Physical Laboratory (NPL) have developed a new lead-free, high temperature ceramic capacitor that could improve the efficiency and reliability of electric and hybrid vehicles.

Invisibility cloaks may be just around the corner

In 1897, H.G. Wells created a fictional scientist who became invisible by changing his refractive index to that of air, so that his body could not absorb or reflect light. More recently, Harry Potter disappeared from sight ...

Beyond the looking glass...

While the researchers can't promise delivery to a parallel universe or a school for wizards, books like Pullman's Dark Materials and JK Rowling's Harry Potter are steps closer to reality now that researchers in China have ...

Storing a Lightning Bolt in Glass for Portable Power

(PhysOrg.com) -- Materials researchers at Penn State University have reported the highest known breakdown strength for a bulk glass ever measured. Breakdown strength, along with dielectric constant, determines how much energy ...

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Permittivity

In electromagnetism, absolute permittivity is the measure of the resistance that is encountered when forming an electric field in a medium. In other words, permittivity is a measure of how an electric field affects, and is affected by, a dielectric medium. The permittivity of a medium describes how much electric field (more correctly, flux) is 'generated' per unit charge. Less electric flux exists in a medium with a high permittivity (per unit charge) due to polarization effects. Permittivity is directly related to electric susceptibility, which is a measure of how easily a dielectric polarizes in response to an electric field. Thus, permittivity relates to a material's ability to transmit (or "permit") an electric field.

In SI units, permittivity ε is measured in farads per meter (F/m); electric susceptibility χ is dimensionless. They are related to each other through

where εr is the relative permittivity of the material, and = 8.85… × 10−12 F/m is the vacuum permittivity.

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