Electrical phenomena Electrical phenomena Avalanche breakdown is a phenomena that can occur in both insulating and semiconducting materials, it is a form of current multiplication which can allow very large currents to flow in situations where that would normally not be possible. Avalanche breakdown occurs when the voltage applied across a material is great enough that free electrons are accelerated to the point that, when they strike an atom in the material, they can knock other electrons free. This phenomena is mostly useful in semiconductor diodes such as the avalanche diode and avalanche photodiode, however in other situations such as in MOSFET transistors, it can be a destructive effect. When avalanche breakdown occurs in an insulating material it is almost always destructive. When an avalanche like effect occures without connecting two electrodes, it is refered to as an Electron avalanche. Although there are some superficial similarities to Zener breakdown, this is a very different effect. ...more on Wikipedia about "Avalanche breakdown"
In the late 18th century, scientists developed sensitive instruments for detecting 'electrification', otherwise known as electrostatic charge imbalance. The phenomenon of electrification by contact, or contact electrification or contact tension, was quickly discovered. When two objects were touched together, sometimes the objects became spontaneously charged. One object developed a net negative charge, while the other developed an equal and opposite positive charge. ...more on Wikipedia about "Contact electrification"
The electromagnetic dawn chorus is an unexplained phenomenon that occurs most often at sunrise or shortly after, that (with the proper radio equipment) resembles the sound of the birds' dawn chorus. It is thought to be caused by high- energy electrons that get caught in the Van Allen radiation belts of the Earth's magnetosphere and fall to the Earth's surface in the form of audible radio waves. Dawn choruses occur more frequently during magnetic storms. ...more on Wikipedia about "Dawn chorus (electromagnetic)"
Electret (formed of elektr- from " electricity" and -et from " magnet") is material that has a permanent electric charge polarisation. The magnetic equivalent is a permanent magnet. Oliver Heaviside coined this term. ...more on Wikipedia about "Electret"
Electrical conduction is the movement of electrically charged particles through a transmission medium. The movement can form an electric current in response to an electric field. The underlying mechanism for this movement depends on the material. ...more on Wikipedia about "Electrical conduction"
Electrical conductivity is a measure for this phenomenon. When a difference of electrical potential is placed across a conductor, its movable charges flow, and an electric current appears. The conductivity σ is defined as the ratio of the current density to the electric field strength : ...more on Wikipedia about "Electrical conductivity"
Electrical phenomena are commonplace and unusual events that can be observed which illuminate the principles of the physics of electricity and are explained by them. ...more on Wikipedia about "Electrical phenomena"
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Electroluminescence (EL) is an optical phenomenon and electrical phenomenon where a material emits light in response to an electric current passed through it, or to a strong electric field. This is distinct to light emission resulting from heat ( incandescence) or from the action of chemicals ( chemoluminescence). ...more on Wikipedia about "Electroluminescence"
An electron avalanche is a process in which a number of free electrons in a medium (usually a gas) are subjected to a strong electric field accelerate, ionizing the mediums' atoms by collision (called Impact ionization), forming "new" electrons to undergo the same process in successive cycles. Streamers in lightning discharges propagate by formation of electron avalanches with the streamers' high electric field strength moves ahead of the advancing tips. Avalanche processes can be intensified by the formation of photoelectrons as a result of ultraviolet radiation emitted by the excited medium's atoms in the aft-tip region ...more on Wikipedia about "Electron avalanche"
An electrostatic discharge (ESD) is an electric current driven by an excess electric charge stored on an electrically insulated object. The term is usually used in the electronics and other industries to describe momentary unwanted currents that cause damage to electronic equipment. ...more on Wikipedia about "Electrostatic discharge"
In physics, the ferroelectric effect is an electrical phenomenon whereby certain ionic crystals and piezoelectric polymers may exhibit a spontaneous dipole moment, which can be reversed by the application of an electric field. The term ferroelectricity is used in analogy to ferromagnetism, in which a material exhibits a permanent magnetic moment. ...more on Wikipedia about "Ferroelectric effect"
Multiferroics are materials which possess two or more switchable states. These switchable states could be electric polarization and magnetic polarization. Multiferroic materials with both ferroelectric and ferromagnetic behavior are also reffered to as ferroelectromagnets or magnetic ferroelectrics. ...more on Wikipedia about "Multiferroics"
Photoconductivity is an optical and electrical phenomenon in which a material becomes more conductive due to the absorption of electro-magnetic radiation such as visible light, ultraviolet light, or gamma radiation. To be photoconductive a semiconductor must be in thermal equilibrium, which contains free electrons and holes. When light is absorbed by the semiconductor, the configuration of electrons and holes changes and raises the electrical conductivity of the semiconductor. To cause excitation the light that strikes the semiconductor must have enough energy to raise electrons across the forbidden bandgap or by exciting the impurities within the bandgap. When a bias voltage and a load resistor are used in series with the semiconductor, a voltage drop across the load resistors can be measured when the change in electrical conductivity varies the current flowing through the circuit. A classic example of photoconduction is in the polymer polyvinylcarbazole which is used extensively in photocoping. ...more on Wikipedia about "Photoconductivity"
The photoelectric effect is the emission of electrons from matter upon the absorption of electromagnetic radiation, such as ultraviolet radiation or x-rays. An older term for the photoelectric effect was the Hertz effect, though this phrase has fallen out of current use. ** ...more on Wikipedia about "Photoelectric effect"
Piezoelectricity is the ability of certain crystals to generate a voltage in response to applied mechanical stress. The word is derived from the Greek piezein, which means to squeeze or press. The piezoelectric effect is reversible in that piezoelectric crystals when subjected to an externally applied voltage, can change shape by a small amount. The deformation, about 0.1% of the original dimension in PZT, is of the order of nanometers, but nevertheless finds useful applications such as the production and detection of sound, generation of high voltages, electronic frequency generation, and ultrafine focusing of optical assemblies. ...more on Wikipedia about "Piezoelectricity"
The piezoresistive effect describes the changing electrical resistance of a material due to applied mechanical stress. The piezoresistive effect differs from the piezoelectric effect. In contrast to the piezoelectric effect, the piezoresistive effect only causes a change in resistance, it does not produce electrical charges. ...more on Wikipedia about "Piezoresistive effect"
Positive Temperature Coefficient (PTC) referers to materials that when temperature is raised, the electrical resistance increases sharply. The higher the coefficient, the greater an increase in electrical resistance for a given temperature increase. ...more on Wikipedia about "Positive temperature coefficient"
Pyroelectricity is the ability of certain materials to generate an electrical potential when they are heated or cooled. As a result of this change in temperature, positive and negative charges move to opposite ends through migration (i.e. the material becomes polarised) and hence, an electrical potential is established. ...more on Wikipedia about "Pyroelectricity"
St. Elmo's Fire is an electro- luminescent corona discharge caused by the ionization of the air during thunderstorms inside of a strong electric field. Although referred to as "fire", St. Elmo's Fire is in fact a low density, relatively low temperature plasma caused by massive atmospheric electrical potential differences which exceed the dielectric breakdown value of air at around 3 megavolts per meter. St. Elmo's Fire is named after Erasmus of Formiae (also called St. Elmo), the patron saint of sailors (who sometimes held its appearance to be auspicious). ...more on Wikipedia about "St. Elmo's fire"
The triboelectric effect is a type of contact electrification in which certain materials become electrically charged after 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, ēlektron. Other examples of materials that can acquire a significant charge when rubbed together include glass rubbed with silk, and hard rubber rubbed with fur. ...more on Wikipedia about "Triboelectric effect"
In physics, the Volta effect is an obsolete name for the weak potential developed by the contact of different metals. This effect was first discovered by Alessandro Volta, and can be measured using a capacitance electroscope ** comprised of different metals. ...more on Wikipedia about "Volta effect" My http://www.shortopedia.com is mine.
A Whistler is a very low frequency radio wave generated by lightning. In addition to Earth they have been received from Jupiter showing the presence of lightning there. ...more on Wikipedia about "Whistler (radio)"
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