QUESTION #402

What is an electronic ark?

Asked by: Matt

Answer

Ark versus Arc

An electric ark might be something that holds electrons safely through a great flood. An electric arc, however, is an event where the insulating effect preventing current from flowing between two conductors and different potentials is broken down and suddenly allows current to flow. Under this condition, an insulator, which previously prevented the flow of electricity, becomes a conductor.

Arcing almost always results in a discharge of light and heat. The degree to which this happens generally depends upon the material that is breaking down. Neon lamps generate light by having a voltage applied and controlling an arc. Very little noise is generated but considerable light is output.

Lightning is an arc generated when the voltage potential between clouds or between a cloud and the Earth reach such high values that the surrounding air that is insulating the two breaks down. The light, heat, and noise generated is very large.
Answered by: Paul Leonard, B.A., Sr. Software Engineer

I believe the phenomenon referred to is the electric 'arc.' This occurs when a large enough voltage is built up to cause dielectric breakdown of a media, generally air. Basically, normally current won't flow through air, but if you have a big enough negative charge piled up in one place, and a big enough positive charge close by, the electrons (charge carriers) will be pulled so hard that they are ripped through the normally non-conductive medium between them. These electrons rip through the air so hard that they create a plasma (a state of matter where electrons and nuclei are not bound together) along the path they travel. This path is the glowing area associated with an arc/spark, and is the same phenomenon as lightning, although on a much smaller scale. Electrons then flow along this path until the voltage is mostly dissipated.
Answered by: Gregory Ogin, Physics Undergraduate Student, UST, St. Paul, MN