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Not to be confused with dialectic. In classical Philosophy, dialectic (διαλεκτική is controversy the exchange of arguments and counter-arguments respectively advocating Propositions

A 'dielectric' is a nonconducting substance, i. e. an insulator. An insulator, also called a Dielectric, is a material that resists the flow of Electric current. The term was coined by William Whewell[1] in response to a request from Michael Faraday. William Whewell ( May 24, 1794 &ndash March 6, 1866) was an English Polymath, Scientist, Anglican Priest Michael Faraday, FRS ( September 22 1791 – August 25 1867) was an English Whewell considered "dia-electric", from the Greek "dia" meaning "through", since an electric field passes through the material but felt that "dielectric" was easier to pronounce. Although "dielectric" and "insulator" are generally considered synonymous, the term "dielectric" is more often used when considering the effect of alternating electric fields on the substance while "insulator" is more often used when the material is being used to withstand a high electric field. Von Hippel, in his seminal book [2] takes this definition further. He states,

"Dielectrics . . . are not a narrow class of so-called insulators, but the broad expanse of nonmetals considered from the standpoint of their interaction with electric, magnetic, of electromagnetic fields. Thus we are concerned with gases as well as with liquids and solids, and with the storage of electric and magnetic energy as well as its dissipation. "

Dielectrics is the study of dielectric materials and involves physical models to describe how an electric field behaves inside a material. 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 (that can It is characterised by how an electric field interacts with an atom and is therefore possible to approach from either a classical interpretation or a quantum one. Classical electromagnetism (or classical electrodynamics) is a theory of Electromagnetism that was developed over the course of the 19th century most prominently Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons

Many phenomena in electronics, solid state and optical physics can be described using the underlying assumptions of the dielectric model. Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical Solid-state physics, the largest branch of Condensed matter physics, is the study of rigid Matter, or Solids The bulk of solid-state physics theory and This can mean that the same mathematical objects can go by many different names.

Contents

Definitions

Electric field interaction with an atom under the classical dielectric model.
Electric field interaction with an atom under the classical dielectric model.

Classical

In the classical approach to the dielectric model, a material is made up of atoms. Each atom consists of a cloud of negative charge bound to and surrounding a positive point charge at its centre. Because of the comparatively huge distance between them, none of the atoms in the dielectric material interact with one another. Note: Remember that the model is not attempting to say anything about the structure of matter. It is only trying to describe the interaction between an electric field and matter.

In the presence of an electric field the charge cloud is distorted, as shown in the top right of the figure. 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 (that can

This can be reduced to a simple dipole using the superposition principle. In physics there are two kinds of dipoles ( Hellènic: di(s- = two- and pòla = pivot hinge An electric dipole is a In Physics and Systems theory, the superposition principle, also known as superposition property, states that for all Linear systems A dipole is characterized by its dipole moment, a vector quantity shown in the figure as the blue arrow labeled M. In Physics, the electric dipole moment (or electric dipole for short is a measure of the polarity of a system of Electric charges. It is the relationship between the electric field and the dipole moment that gives rise to the behavior of the dielectric. Note: The dipole moment is shown to be pointing in the same direction as the electric field. This isn't always correct, and it is a major simplification, but it is suitable for many materials.

When the electric field is removed the atom returns to its original state.

Behavior

This is the essence of the model. The behavior of the dielectric now depends on the situation. The more complicated the situation the more rich the model has to be in order to accurately describe the behavior. Important questions are:

The relationship between the electric field E and the dipole moment M gives rise to the behavior of the dielectric, which, for a given material, can be characterized by the function F defined by the equation: \mathbf{M} = \mathbf{F}(\mathbf{E}). Isotropy is uniformity in all directions Precise definitions depend on the subject area For other uses see Homogeneous. In Physics, homogeneous mixtures are mixtures that have definite consistent composition and properties A linear system is a mathematical model of a System based on the use of a Linear operator. This article describes the use of the term nonlinearity in mathematics

When both the type of electric field and the type of material have been defined, one then chooses the simplest function F that correctly predicts the phenomena of interest. Examples of possible phenomena:

May be modeled by choosing a suitable function F. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium In Optics, dispersion is the phenomenon in which the Phase velocity of a wave depends on its frequency Birefringence, or double refraction, is the decomposition of a ray of Light into two rays (the ordinary ray and the extraordinary ray Self-focusing is a non-linear optical process induced by the change in Refractive index of materials exposed to intense Electromagnetic radiation. Perturbative Harmonic Generation Perturbative Harmonic Generation is a process where by laser lightof frequency ω and photon energy ħω can be usedto generate new

Dielectric model applied to vacuum

From the definition it might seem strange to apply the dielectric model to a vacuum, however, it is both the simplest and the most accurate example of a dielectric.

Recall that the property which defines how a dieletric behaves is the relationship between the applied electric field and the induced dipole moment. For a vacuum the relationship is a real constant number. In Mathematics, the real numbers may be described informally in several different ways This constant is called the permittivity of free space, ε0. Vacuum permittivity, referred to by international standards organizations as the electric constant, and denoted by the symbol ε0 is a fundamental Physical

Applications

Capacitors

Commercially manufactured capacitors typically use a solid dielectric material with high permittivity as the intervening medium between the stored positive and negative charges. A capacitor is a passive electrical component that can store Energy in the Electric field between a pair of conductors A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. Permittivity is a Physical quantity that describes how an Electric field affects and is affected by a Dielectric medium and is determined by the ability This material is often referred to in technical contexts as the "capacitor dielectric" [3] . The most obvious advantage to using such a dielectric material is that it prevents the conducting plates on which the charges are stored from coming into direct electrical contact. More significantly however, a high permittivity allows a greater charge to be stored at a given voltage. This can be seen by treating the case of a linear dielectric with permittivity ε and thickness d between two conducting plates with uniform charge density σε. In this case, the charge density is given by

\sigma_{\epsilon}=\epsilon\frac{V}{d}

and the capacitance per unit area by

c=\frac{\sigma_{\epsilon}}{V}=\frac{\epsilon}{d}

From this, it can easily be seen that a larger ε leads to greater charge stored and thus greater capacitance. Capacitance is a measure of the amount of Electric charge stored (or separated for a given Electric potential.

Dielectric materials used for capacitors are also chosen such that they are resistant to ionization. Ionization is the physical process of converting an Atom or Molecule into an Ion by adding or removing charged particles such as Electrons This allows the capacitor to operate at higher voltages before the insulating dielectric ionizes and begins to allow undesirable current flow.

Cable insulation

The term "dielectric" may also refer to the insulation used in power and RF cables.

Some practical dielectrics

Dielectric materials can be solids, liquids, or gases. In addition, a high vacuum can also be a useful, lossless dielectric even though its relative dielectric constant is only unity.

Solid dielectrics are perhaps the most commonly used dielectrics in electrical engineering, and many solids are very good insulators. Some examples include porcelain, glass, and most plastics. Porcelain is a Ceramic material made by heating raw materials generally including Clay in the form of Kaolin, in a Kiln to temperatures Glass in the common sense refers to a Hard, Brittle, transparent Solid, such as that used for Windows many Plastic is the general common term for a wide range of synthetic or semisynthetic organic solid materials suitable for the manufacture of industrial products Air, nitrogen and sulfur hexafluoride are the three most commonly used gaseous dielectrics. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Sulfur hexafluoride is an Inorganic compound with the formula.

See also

References

  1. ^ J. A capacitor is a passive electrical component that can store Energy in the Electric field between a pair of conductors In Physics, the term dielectric strength has the following meanings Of an insulating material the maximum electric Field strength that it can withstand Measurement The relative static permittivity εr can be measured for static Electric fields as follows first the Capacitance of a test A dielectric resonator is an electronic component that exhibits Resonance for a narrow range of frequencies generally in the Microwave band Dielectric Spectroscopy (sometimes called impedance spectroscopy) measures the Dielectric properties of a medium as a function of Frequency The electric susceptibility χe of a Dielectric material is a measure of how easily it polarizes in response to an Electric field. Electrorotation is the circular movement of an electrically polarized particle In Semiconductor manufacturing a Low-κ Dielectric is a material with a small Dielectric constant relative to silicon dioxide Permittivity is a Physical quantity that describes how an Electric field affects and is affected by a Dielectric medium and is determined by the ability Vacuum permittivity, referred to by international standards organizations as the electric constant, and denoted by the symbol ε0 is a fundamental Physical The term high-κ Dielectric refers to a material with a high Dielectric constant (κ (as compared to Silicon dioxide) used in semiconductor manufacturing Leakage describes an unwanted loss or Leak, of something which escapes from its proper location Electret (formed of elektr- from " Electricity " and -et from " Magnet " is a Dielectric material that has a quasi-permanent Piezoelectricity is the ability of some materials (notably Crystals and certain Ceramics including bone to generate an Electric potential in response to Ferroelectricity is a physical property of a material whereby it exhibits a spontaneous electric polarization, the direction of which can be switched between equivalent Daintith, "Biographical Encyclopedia of Scientists" CRC Press, 1994, ISBN 0750302879, page 943
  2. ^ A. R. Von Hippel (ed), "Dielectric Materials and Applications", published jointly by the Technology Press of MIT and John Wiley, NY, 1954
  3. ^ States7113388 United States patent 7113388, "Semiconductor capacitor with praseodymium oxide as dielectric", granted 2004-10-18, assigned to IHP GmbH- Innovations for High Performance Microelectronics/Institute Fur Innovative Mikroelektronik 

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Dictionary

dielectric

-noun

  1. (physics) An electrically insulating or nonconducting material.
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