Engineers discover a high-speed nano-avalanche

Charles McLaren, a doctoral student in materials science and engineering at Lehigh University, arrived last fall for his semester of research at the University of Marburg in Germany with his language skills significantly ...

NASA study finds solar storms could spark soils at moon's poles

Powerful solar storms can charge up the soil in frigid, permanently shadowed regions near the lunar poles, and may possibly produce "sparks" that could vaporize and melt the soil, perhaps as much as meteoroid impacts, according ...

'Ideal' energy storage material for electric vehicles developed

The energy-storage goal of a polymer dielectric material with high energy density, high power density and excellent charge-discharge efficiency for electric and hybrid vehicle use has been achieved by a team of Penn State ...

IBM introduces new graphene transistor

(PhysOrg.com) -- In a report published in Nature, Yu-ming Lin and Phaedon Avoris, IBM researchers, have announced the development of a new graphene transistor which is smaller and faster than the one they introduced in February ...

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 ...

Sol-gel capacitor dielectric offers record-high energy storage

Using a hybrid silica sol-gel material and self-assembled monolayers of a common fatty acid, researchers have developed a new capacitor dielectric material that provides an electrical energy storage capacity rivaling certain ...

Artificial muscle for soft robotics: Low voltage, high hopes

Soft robots do a lot of things well but they're not exactly known for their speed. The artificial muscles that move soft robots, called actuators, tend to rely on hydraulics or pneumatics, which are slow to respond and difficult ...

New material holds big energy hope

(Phys.org) —A new material that can store large amounts of energy with very little energy loss has been developed by researchers at the Australian National University.

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Dielectric

A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material, as in a conductor, but only slightly shift from their average equilibrium positions causing dielectric polarization. Because of dielectric polarization, positive charges are displaced toward the field and negative charges shift in the opposite direction. This creates an internal electric field which reduces the overall field within the dielectric itself. If a dielectric is composed of weakly bonded molecules, those molecules not only become polarized, but also reorient so that their symmetry axis aligns to the field.

Although the term "insulator" implies low electrical conduction, "dielectric" is typically used to describe materials with a high polarizability. The latter is expressed by a number called the dielectric constant. A common, yet notable example of a dielectric is the electrically insulating material between the metallic plates of a capacitor. The polarization of the dielectric by the applied electric field increases the capacitor's surface charge.

The study of dielectric properties is concerned with the storage and dissipation of electric and magnetic energy in materials. It is important to explain various phenomena in electronics, optics, and solid-state physics.

The term "dielectric" was coined by William Whewell (from "dia-electric") in response to a request from Michael Faraday.

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