Triboelectric effect
The triboelectric effect is an electrical phenomenon where certain materials, for example, glass, hard rubber, amber, or even the seat of one's pants, become electrically charged after coming into contact with another, different, material.Although the word comes from the Greek for "rubbing", tribos, the two materials only need to come into contact and then separate for electrons to be exchanged. However, the effect is greatly enhanced by rubbing the materials together, as they touch and separate many times.
For example, glass rubbed with silk will build up a charge, as will hard rubber rubbed with fur. The polarity and strength of the charges produced differ according to material and surface smoothness.
Because the material is now electrically charged, either negatively or positively, contact with an uncharged object or one with a substantially different charge may cause a discharge of the built-up static electricity; a spark. A person simply walking across a carpet may build up a charge of many thousands of volts, enough to cause a spark a centimeter long or more (this type of discharge is usually harmless, as it is passes very little current).
The effect is of considerable industrial importance both in terms of safety and also potential damage to manufactured goods. The spark produced is fully capable of igniting inflammable vapours, for example, petrol or ether fumes. Means have to be found to discharge hospital trolleys which may carry such liquids.
Even where only a small charge is produced, this can result in dust particles being attracted to the rubbed surface. In the case of textile manufacture this can lead to a permanent grimy mark where the cloth has been charged.
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