FACTOID # 21: 15% of Army recruits from South Dakota are Native American, which is roughly the same percentage for female Army recruits in the state.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Dielectric constant
Dielectric constants of some materials at room temperature
Material Dielectric constant
Vacuum 1 (by definition)
Air 1.00054
Polyethylene 2.25
Paper 3.5
PTFE (Teflon(TM)) 2.1
Polystyrene 2.4-2.7
Pyrex glass 4.7
Rubber 7
Silicon 11.68
Methanol 30
Concrete 4.5
Water (20°C) 80.10
Barium titanate 1200

The relative dielectric constant of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux. It is the ratio of the amount of stored electrical energy when a potential is applied, relative to the permittivity of a vacuum. It is also called relative permittivity. Room temperature describes a certain temperature within enclosed space that is uses for various purposes by human beings. ... Look up Vacuum in Wiktionary, the free dictionary. ... Layers of Atmosphere (NOAA) Air redirects here. ... This article or section does not cite its references or sources. ... A blank sheet of paper Paper is a commodity of thin material produced by the amalgamation of fibers, typically vegetable fibers composed of cellulose, which are subsequently held together by hydrogen bonding. ... Polystyrene is a polymer made from the monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry. ... Pyrex is a brand name of borosilicate glass introduced by Corning Glass Works in 1915. ... Latex being collected from a tapped rubber tree Rubber is an elastic hydrocarbon polymer which occurs as a milky colloidal suspension (known as latex) in the sap of several varieties of plants. ... It has been suggested that Silicons ranking be merged into this article or section. ... Methanol, also known as methyl alcohol, carbinol, wood alcohol or wood spirits, is a chemical compound with chemical formula CH3OH. It is the simplest alcohol, and is a light, volatile, colourless, flammable, poisonous liquid with a distinctive odor that is somewhat milder and sweeter than ethanol (ethyl alcohol). ... Concrete being poured, raked and vibrated into place in residential construction in Toronto, Ontario, Canada. ... Impact of a drop of water Water is a chemical substance that is essential to all known forms of life[1]. It covers 71% of Earths surface. ... Barium titanate is an oxide of barium and titanium with the chemical formula BaTiO3. ... Electrostatics is the branch of physics that deals with the force exerted by a static (i. ... 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 of a material to polarize in response to an applied electric field, and thereby to cancel, partially, the field inside the material. ...


The dielectric constant is represented as εr or sometimes κ or K or Dk. It is defined as

varepsilon_{r} = frac{varepsilon_{s}}{varepsilon_{0}}

where εs is the static permittivity of the material, and ε0 is vacuum permittivity. Vacuum permittivity is derived from Maxwell's equations by relating the electric field intensity E to the electric flux density D. In vacuum (free space), the permittivity ε is just ε0, so the dielectric constant is 1. 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 of a material to polarize in response to an applied electric field, and thereby to cancel, partially, the field inside the material. ... In electromagnetism, Maxwells equations are a set of equations, developed in the latter half of the nineteenth century by James Clerk Maxwell. ... Electric Field :Electric field intensity is known as the space surrounding a charge particle in which any other particle feels a force of attraction or repulsion. ... In physics, the electric displacement field or electric flux density is a vector-valued field that appears in Maxwells equations and that generalizes the electric field. ... In physics, free space is a concept of electromagnetic theory, corresponding roughly to the vacuum, the baseline state of the electromagnetic field, or the replacement for the electromagnetic aether. ...


The relative permittivity of a medium is related to its electric susceptibility, χe by It has been suggested that this article or section be merged into permittivity. ...

varepsilon_r = 1 + chi_e.

Contents

Measurement

The relative dielectric constant εr can be measured for static electric fields as follows: first the capacitance of a test capacitor C0 is measured with vacuum between its plates. Then, using the same capacitor and distance between its plates the capacitance Cx with a dielectric between the plates is measured. The relative dielectric constant can be then calculated as: It has been suggested that optical field be merged into this article or section. ... Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential. ...

varepsilon_{r} = frac{C_{x}} {C_{0}}

For time-varying electromagnetic fields, the dielectric constant of materials becomes frequency dependent and in general is called permittivity. This article or section may be confusing or unclear for some readers, and should be edited to rectify this. ... FreQuency is a music video game developed by Harmonix and published by SCEI. It was released in November 2001. ... 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 of a material to polarize in response to an applied electric field, and thereby to cancel, partially, the field inside the material. ...


Practical relevance

The dielectric constant is an essential piece of information when designing capacitors, and in other circumstances where a material might be expected to introduce capacitance into a circuit. If a material with a high dielectric constant is placed in an electric field, the magnitude of that field will be measurably reduced within the volume of the dielectric. This fact is commonly used to increase the capacitance of a particular capacitor design. The layers beneath etched conductors in Printed Circuit Boards (PCBs) also act as dielectrics. Capacitors: SMD ceramic at top left; SMD tantalum at bottom left; through-hole tantalum at top right; through-hole electrolytic at bottom right. ... Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential. ... It has been suggested that optical field be merged into this article or section. ... PCB may refer to: Brazilian Communist Party (in Portuguese, Partido Comunista Brasileiro) Communist Party of Bolivia (in Spanish, Partido Comunista de Bolivia) Pakistan Cricket Board PCBoard, a bulletin board system software Police Complaints Board, which oversaw the system for handling complaints made against police forces in England and Wales until...


Dielectrics are used in RF transmission lines. In a coaxial cable, polyethylene can be used between the center conductor and outside shield. It can also be placed inside waveguides to form filters. RF may mean: RF, the IATA code for Florida West International Airways RF, NYSE ticker symbol for Regions Financial Corporation Royalty free Rf or RF may stand for: Radio frequency Volumetric flow rate/rate of flow (Rf) RF connectors, electrical connectors designed to work at radio frequencies Red Faction, a... coaxial cable In geometry, coaxial means that two or more forms share a common axis; it is the three-dimensional analog of concentric. Coaxial cable, for example, has a conducting wire in the center and a second conducting layer running all the way around the exterior circumference, under the insulation. ... This article or section does not cite its references or sources. ...


Optical fibers are examples of dielectric waveguides. They consist of dielectric materials that are purposely doped with impurities so as to control the precise value of εr within the cross-section. This controls the refractive index of the material and therefore also the optical modes of transmission. Doped fiber can also be configured to form an optical amplifier. Fiber Optic strands An optical fiber in American English or fibre in British English is a transparent thin fiber for transmitting light. ... Look up waveguide in Wiktionary, the free dictionary. ... An optical amplifier is a device that amplifies an optical signal directly, without the need to first convert it to an electrical signal. ...


Chemical applications

The dielectric constant of a solvent is a relative measure of its polarity. For example, water (very polar) has a dielectric constant of 80.10 at 20°C while n-hexane (very non-polar) has a dielectric constant of 1.89 at 20°C.1 This information is of great value when designing separation, sample preparation and chromatography techniques in analytical chemistry. The polarity of an object is, in general, its physical alignment of atoms. ... This article describes water from a scientific and technical perspective. ... the 3rd ingredient in big mac ...


See also

In physics, the term dielectric strength has the following meanings: Of an insulating material, the maximum electric field strength that it can withstand intrinsically without breaking down, , without experiencing failure of its insulating properties. ... 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 of a material to polarize in response to an applied electric field, and thereby to cancel, partially, the field inside the material. ... A Low-K dielectric is one with a small dielectric constant. ... High K dielectric may be used in next generation electronic component to replace SiO2 Gate dielectric. ...

References

1) D.R. Lide, Ed. CRC Handbook of Chemistry and Physics, 85th Ed. CRC Press. Boca Raton. 2004. pg. 8-141.


External links

  • Dielectric Constants of common materials

  Results from FactBites:
 
Dielectric constant - Wikipedia, the free encyclopedia (533 words)
Electrically, the dielectric constant is a measure of the extent to which a substance concentrates the electrostatic lines of flux.
For time-varying electromagnetic fields, the dielectric constant of materials becomes frequency dependent and in general is called permittivity.
The dielectric constant is an essential piece of information when designing capacitors, and in other circumstances where a material might be expected to introduce capacitance into a circuit.
Dielectric - Wikipedia, the free encyclopedia (401 words)
A dielectric, or electrical insulator, is a substance that is highly resistant to flow of electric current.
Dielectrics are more resistant to ionization than air, so a capacitor containing a dielectric can be subjected to a higher voltage.
Layers of dielectric are commonly incorporated in manufactured capacitors to improve their performance above that of capacitors with only air or a vacuum between their plates, and the term dielectric refers to this application as well as the insulation used in power and RF cables.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m