Dielectric Strength of Air
An educational, fair use website
| Bibliographic Entry | Result (w/surrounding text) |
Standardized Result |
|---|---|---|
| Tipler, Paul A. College Physics. Worth, 1987: 467. | "This phenomenon, which is called dielectric breakdown, occurs in air at an electric field strength of about Emax = 3 × 106 V/m." | 3 × 106 V/m |
| Rigden, John S. Macmillan Encyclopedia of Physics. Simon & Schuster, 1996: 353. | Air; Dielectric Constant, 1; Strength Es (kV/mm), 3 | 3 × 106 V/m |
| Yager, W. A. Digest on Literature on Dielectrics Volume X. Murray Hill, NJ: Bell Telephone Laboratories, 1947: 44-46. | "Minimum sparking potentials in helium are 146, 161 and 187 volts" | 146 V 161 V 187 V |
| Hodgman, Charles D. & Norbert A. Lange. Handbook of Chemistry and Physics 10th Edition. Cleveland, OH: Chemical Rubber Publishing Co, 1925: 547. | "Spark length (cm), .10; Point electrodes, 3720; Ball electrodes, 1 cm diameter: Steady potential, 4560; Alternating potential, 4400" | 3.7–4.5 × 106 V/m |
| Riley, Lewis A. Dielectrics. 1999-2000. | "The dielectric strength of air is about 3 × 106 V/m" | 3 × 106 V/m |
Dielectric breakdown occurs when a charge buildup exceeds the electrical limit or dielectric strength of a material. The negatively charged electrons are pulled in one direction and the positively charged ions in the other. When electrons are removed from a nucleus, it becomes positively charged. When air molecules become ionized in a very high electric field, the air changes from an insulator to a conductor. Sparks occur because of the recombination of electrons and ions. Lightning occurs when there is a buildup of charge on the clouds and the ground It produces the electric field that exceeds the dielectric strength of air. Ionized air is a good conductor and provides a path where by charges can flow from clouds to ground.
The dielectric strength of air is approximately 3 kV/mm. Its exact value varies with the shape and size of the electrodes and increases with the pressure of the air.
Alice Hong -- 2000
External links to this page:
- US Patent 7,569,112, Scanning probe apparatus with in-situ measurement probe tip cleaning capability, Lin Zhou, et al. 2009