Static electricity
|
|
Static electricity or electrostatics is a field of science and a class of phenomena involving the imbalanced charge present on an object, typically referring to charge with voltage of sufficient magnitude to produce visible attraction, repulsion, and sparks.
| Contents |
Generation
The presence of surface charge imbalance means that the objects will exhibit attractive or repulsive forces. Static electricity can be generated by touching two differing surfaces together and then separating them because of contact electrification and the triboelectric effect. Rubbing two non-conductive objects generates a great amount of static electricity. This is NOT the result of friction. In fact two non-conductive surfaces can charge themselves by just being placed on top of each other. But this takes longer since most surfaces have a rough texture. Rubbing them together increases amount of adhesive contact between the two surfaces. Usually, substances that don't conduct electricity (insulators) are good at both generating and holding a surface charge. Some examples of these substances are rubber, plastic, glass, and pith. Conductive objects only rarely will generate charge imbalance, 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. Static electric generators, devices which produce very high voltage at very low current, are frequently used for classroom physics demonstrations.
Note that the presence of electric current does not detract from the electrostatic forces nor from the sparking, from the corona discharge, or other phenomena. In other words, electric current is not the opposite of static electricity, and both phenomena can exist together at the same time.
Effects
Natural electrostatic phenomena are most familiar as an occasional annoyance in seasons of low humidity, but can be destructive and harmful in some situations (e.g. electronics manufacturing.) When working in direct contact with integrated circuit electronics (especially delicate MOSFETs), or in the presence of flammable gas, care must be taken to avoid accumulating and discharging a static charge.
Static is a notorious bugbear for the processing of analog media, because it attracts dust to sensitive materials. In the case of photography, dust accumulating on lenses and plates distorts the resulting picture. Dust also permanently damages vinyl records (it is melted in as the stylus passes by). In both cases several approaches exist to combat such dust formation. Some brushes, particularly those with carbon fiber bristles, are advertised as possessing anti-static properties. Also available are handheld static guns which shoot streams of negative ions to discharge static on records and lenses.
See also
Electronics
Natural
- Triboelectric effect
- Bioelectricity
- Pith
- Cumulonimbus clouds (and Relative humidity)
- Chemical Solutions
- Examples of electrical phenomena
Historical
Other
External links
- Humans and sparks, causes and cures (http://amasci.com/emotor/zapped.html)