Éléktrostatika: Béda antarrépisi

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==Triboelectric series ==
{{mainutama|Triboelectric effect}}
 
The [[triboelectric effect]] is a type of contact electrification in which certain materials become electrically charged when coming into contact with another, different, material, and are then separated. The polarity and strength of the charges produced differ according to the materials, surface roughness, temperature, strain, and other properties. It is therefore not very predictable, and only broad generalizations can be made. Amber, for example, can acquire an electric charge by friction with a material like wool. This property, first recorded by [[Thales of Miletus]], suggested the word "electricity", from the Greek word for amber, èlectròn. Other examples of materials that can acquire a significant charge when rubbed together include glass rubbed with silk, and hard rubber rubbed with fur.
 
==Electrostatic generators==
{{mainutama|Electrostatic generator}}
The presence of [[surface charge]] imbalance means that the objects will exhibit attractive or repulsive forces. This surface charge imbalance, which yields static electricity, can be generated by touching two differing surfaces together and then separating them due to the phenomena of [[contact electrification]] and the [[triboelectric effect]]. Rubbing two nonconductive objects generates a great amount of static electricity. This is not just the result of friction; two nonconductive surfaces can become charged by just being placed one on top of the other. Since most surfaces have a rough texture, it takes longer to achieve charging through contact than through rubbing. Rubbing objects together increases amount of adhesive contact between the two surfaces. Usually [[insulators]], e.g., substances that do not conduct electricity, are good at both generating, and holding, a surface charge. Some examples of these substances are [[rubber]], [[plastic]], [[glass]], and [[pith]]. [[conductor (material)|Conductive]] objects only rarely generate charge imbalance except, for example, when a metal surface is impacted by solid or liquid nonconductors. The charge that is transferred during contact electrification is stored on the surface of each object. [[electrostatic generator|Static electric generators]], devices which produce very high voltage at very low current and used for classroom physics demonstrations, rely on this effect.
 
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=='Static' electricity==
{{mainutama|Static electricity}}
 
Before the year 1832, when [[Michael Faraday]] published the results of his experiment on the identity of electricities, physicists thought "static electricity" was somehow different from other electrical charges. Michael Faraday proved that the electricity induced from the magnet, voltaic electricity produced by a battery, and static electricity are all the same.
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when different materials are brought together and then separated, an accumulation of electric charge can occur which leaves one material positively charged while the other becomes negatively charged. The mild shock that you receive when touching a grounded object after walking on carpet is an example of excess electrical charge accumulating in your body from frictional charging between your shoes and the carpet. The resulting charge build-up within your body can generate a strong electrical discharge. Although experimenting with static electricity may be fun, similar sparks create severe hazards in those industries dealing with flammable substances, where a small electrical spark may ignite explosive mixtures with devastating consequences.
 
A similar charging mechanism can occur within low conductivity fluids flowing through pipelines - a process called flow electrification. Fluids which have low electrical conductivity (below 50 pico siemens/cm, where pico siemens/cm is a measure of electrical conductivity), are called accumulators. Fluids having conductivities above 50 pico siemens/cm are called non-accumulators. In non-accumulators, charges recombine as fast as they are separated and hence electrostatic charge generation is not significant. In the petrochemical industry, 50 pico siemens/cm is the recommended minimum value of electrical conductivity for adequate removal of charge from a fluid.
 
An important concept for insulating fluids is the static relaxation time. This is similar to the time constant (tau) within an [[RC circuit]]. For insulating materials, it is the ratio of the static [[dielectric constant]] divided by the electrical conductivity of the material. For hydrocarbon fluids, this is sometimes approximated by dividing the number 18 by the electrical conductivity of the fluid. Thus a fluid that has an electrical conductivity of 1 pico siemens /cm will have an estimated relaxation time of about 18 seconds. The excess charge within a fluid will be almost completely dissipated after 4 to 5 times the relaxation time, or 90 seconds for the fluid in the above example.
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;Essays and books
*William J. Beaty, "''[http://amasci.com/emotor/zapped.html Humans and sparks; The Cause, Stopping the Pain, and 'Electric People]''". 1997.
*[[William Cecil Dampier]], "''The theory of experimental electricity''". Cambridge [Eng.] University press, 1905 (Cambridge physical series). xi, 334 p. illus., diagrs. 23  cm. LCCN 05040419 //r33
 
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