Difference between revisions of "Insulation"

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==Etymology==
 
==Etymology==
 
[[Latin]] insula
 
[[Latin]] insula
*Date: circa [http://www.wikipedia.org/wiki/18th_Century 1741]
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*Date: circa [https://www.wikipedia.org/wiki/18th_Century 1741]
 
==Definition==
 
==Definition==
 
*to place in a detached situation : [[isolate]]; especially : to separate from conducting [[bodies]] by means of nonconductors so as to prevent transfer of [[electricity]], [[heat]], or [[sound]]
 
*to place in a detached situation : [[isolate]]; especially : to separate from conducting [[bodies]] by means of nonconductors so as to prevent transfer of [[electricity]], [[heat]], or [[sound]]
 
==Description==
 
==Description==
[[Electrical]] '''insulation''' is the [[absence]] of [http://en.wikipedia.org/wiki/Electrical_conduction electrical conduction]. Electronic [http://en.wikipedia.org/wiki/Electronic_band_structure band theory] (a branch of [[physics]]) [[predicts]] that a [[charge]] will [[flow]] whenever there are [[states]] available into which the [[electrons]] in a [[material]] can be excited. This allows them to gain [[energy]] and thereby move through the conductor (usually a metal). If no such states are available, the [[material]] is an insulator.
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[[Electrical]] '''insulation''' is the [[absence]] of [https://en.wikipedia.org/wiki/Electrical_conduction electrical conduction]. Electronic [https://en.wikipedia.org/wiki/Electronic_band_structure band theory] (a branch of [[physics]]) [[predicts]] that a [[charge]] will [[flow]] whenever there are [[states]] available into which the [[electrons]] in a [[material]] can be excited. This allows them to gain [[energy]] and thereby move through the conductor (usually a metal). If no such states are available, the [[material]] is an insulator.
  
Most (though not all, see [http://en.wikipedia.org/wiki/Mott_insulator Mott insulator)] insulators are characterized by having a large [http://en.wikipedia.org/wiki/Band_gap band gap]. This occurs because the "valence" band containing the highest energy electrons is full, and a large energy gap separates this band from the next band above it. There is always some voltage (called the [http://en.wikipedia.org/wiki/Breakdown_voltage breakdown voltage]) that will give the [[electrons]] enough [[energy]] to be excited into this band. Once this voltage is exceeded, the [[material]] ceases being an insulator, and [[charge]] will begin to pass through it. However, it is usually accompanied by [[physical]] or [[chemical]] [[changes]] that permanently degrade the material's insulating properties.
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Most (though not all, see [https://en.wikipedia.org/wiki/Mott_insulator Mott insulator)] insulators are characterized by having a large [https://en.wikipedia.org/wiki/Band_gap band gap]. This occurs because the "valence" band containing the highest energy electrons is full, and a large energy gap separates this band from the next band above it. There is always some voltage (called the [https://en.wikipedia.org/wiki/Breakdown_voltage breakdown voltage]) that will give the [[electrons]] enough [[energy]] to be excited into this band. Once this voltage is exceeded, the [[material]] ceases being an insulator, and [[charge]] will begin to pass through it. However, it is usually accompanied by [[physical]] or [[chemical]] [[changes]] that permanently degrade the material's insulating properties.
  
[[Materials]] that lack [[electron]] conduction are insulators if they lack other mobile [[charges]] as well. For example, if a liquid or gas contains ions, then the ions can be made to [[flow]] as an [[electric]] current, and the material is a conductor. [http://en.wikipedia.org/wiki/Electrolyte Electrolytes] and [http://en.wikipedia.org/wiki/Plasma_(physics) plasmas] contain ions and will act as conductors whether or not electron [[flow]] is involved.[http://en.wikipedia.org/wiki/Insulator_%28electrical%29]
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[[Materials]] that lack [[electron]] conduction are insulators if they lack other mobile [[charges]] as well. For example, if a liquid or gas contains ions, then the ions can be made to [[flow]] as an [[electric]] current, and the material is a conductor. [https://en.wikipedia.org/wiki/Electrolyte Electrolytes] and [https://en.wikipedia.org/wiki/Plasma_(physics) plasmas] contain ions and will act as conductors whether or not electron [[flow]] is involved.[https://en.wikipedia.org/wiki/Insulator_%28electrical%29]
  
 
[[Category: Physics]]
 
[[Category: Physics]]

Latest revision as of 23:56, 12 December 2020

Lighterstill.jpg

Electrical-insulation.jpg

Etymology

Latin insula

Definition

  • to place in a detached situation : isolate; especially : to separate from conducting bodies by means of nonconductors so as to prevent transfer of electricity, heat, or sound

Description

Electrical insulation is the absence of electrical conduction. Electronic band theory (a branch of physics) predicts that a charge will flow whenever there are states available into which the electrons in a material can be excited. This allows them to gain energy and thereby move through the conductor (usually a metal). If no such states are available, the material is an insulator.

Most (though not all, see Mott insulator) insulators are characterized by having a large band gap. This occurs because the "valence" band containing the highest energy electrons is full, and a large energy gap separates this band from the next band above it. There is always some voltage (called the breakdown voltage) that will give the electrons enough energy to be excited into this band. Once this voltage is exceeded, the material ceases being an insulator, and charge will begin to pass through it. However, it is usually accompanied by physical or chemical changes that permanently degrade the material's insulating properties.

Materials that lack electron conduction are insulators if they lack other mobile charges as well. For example, if a liquid or gas contains ions, then the ions can be made to flow as an electric current, and the material is a conductor. Electrolytes and plasmas contain ions and will act as conductors whether or not electron flow is involved.[1]