Contact Electrification

Contact electrification is an superseded scientific theory from the Enlightenment that attempted to account for all the sources of electric charge known at the time. 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 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. Then it was discovered that 'piles' of dissimilar metal disks separated by acid-soaked cloth, Voltaic piles, could also produce charge differences. Although it was later found that these effects were caused by different physical processes - triboelectricity, the Volta effect, differing work functions of metals, and others - at the time they were all thought to be caused by a common 'contact electrification' process.

The contact electrification phenomenon allowed the construction of so-called 'frictional' electrostatic generators such as Ramsden's or Winter's machines, but it also led directly to the development of much modern electrical technology such as batteries, fuel cells, electroplating, thermocouples, and semiconductor junction devices including radio detector diodes, photocells, LEDs, and thermoelectric cells.

Read more about Contact Electrification:  History, Triboelectric Contact, Electrolytic-metallic Contact, Metallic Contact, Semiconductor Contact

Famous quotes containing the word contact:

    ET phone home.
    Melissa Mathison, U.S. screenwriter, and Steven Spielberg. ET, ET The Extra-Terrestrial, realizing he can contact his home planet (1982)