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Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it can move away by an electric current or electrical discharge . The word "static" is used to differentiate it from current electricity , where an electric charge flows through an electrical conductor .
If the electric field in a system can be assumed to result from static charges, that is, a system that exhibits no significant time-varying magnetic fields, the system is justifiably analyzed using only the principles of electrostatics. This is called the "electrostatic approximation". [12]
The surface is the only location where a net electric charge can exist. [4]: p.754 This establishes the principle that electrostatic charges on conductive objects reside on the surface of the object. [3] [7] External electric fields induce surface charges on metal objects that exactly cancel the field within. [3]
Electrostatic discharge (ESD) is a sudden and momentary flow of electric current between two differently-charged objects when brought close together or when the dielectric between them breaks down, often creating a visible spark associated with the static electricity between the objects.
< 10 −3: 10 −3 to 1 1 to 10 3: 10 3 to 10 6: 10 6 to 10 9: 10 9 to 10 12 > 10 13: Material Metals: Carbons: Shielding Conductive Static Dissipative Anti-Static Insulative: Description Carbon powders and fiber: No initial charge. Provides path for charge to bleed off. Typically black color. No or low initial charge. Prevents discharge to or ...
Electrostatic machines are typically used in science classrooms to safely demonstrate electrical forces and high voltage phenomena. The elevated potential differences achieved have been also used for a variety of practical applications, such as operating X-ray tubes, particle accelerators, spectroscopy, medical applications, sterilization of food, and nuclear physics experiments.
Experiments involving triboelectricity and static electricity occurred before the discovery of the electron. The name ēlektron (ἤλεκτρον) is Greek for amber, [10] [11] which is connected to the recording of electrostatic charging by Thales of Miletus around 585 BCE, [12] and possibly others even earlier.
Electric discharges can convey substantial energy to the electrodes at the ends of the discharge. A spark gap is used in internal combustion engines to ignite the fuel/air mixture on every power stroke. Spark gaps are also used to switch heavy currents in a Marx generator and to protect electrical apparatus.