Performance size
In different contexts, especially of electrical engineering and acoustics (eg. As audio level , voltage gain , shielding effectiveness ) are physical quantities not stated directly, but only as a ratio to a second variable or fixed size of the same type. Preferably, the two sizes the ratio of which is specified, in each case by performance quantities or performance root quantities .
If the ratios extend over several powers of ten , it makes sense to specify them as a logarithmic quantity .
Performance size
A performance quantity is a quantity that is proportional to a performance .
- Examples: electrical power , electromagnetic and acoustic power and associated power densities
In this context, energy quantities, i.e. quantities that are related to an energy , are also referred to as power quantities .
- Examples: electrical energy , electromagnetic and acoustic energy and associated energy densities ( sound power , sound intensity , sound energy density )
Achievement root size
A performance root quantity is a quantity whose square is proportional to a performance quantity. Power root quantities were previously referred to as field quantities .
- Examples: electrical voltage , electrical current strength , electrical and magnetic field strength , electrical and magnetic flux density , sound pressure , sound velocity
Power root quantities are usually effective values ; for a sine- shaped alternating quantity their can amplitude , complex amplitude or its complex RMS may be used.
Logarithmic ratios
Determinations |
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Logarithmic ratio with field sizes Logarithmic ratio with performance quantities |
- or with the complex sizes :
literature
- Horst Clausert, Gunther Wiesemann, Volker Hinrichsen , Jürgen Stenzel: Basic areas of electrical engineering. Volume 2: Alternating currents, three-phase currents, cables, applications of Fourier, Laplace and Z transformation. 11th, corrected edition. Oldenbourg, Munich et al. 2011, ISBN 978-3-486-59719-6 .
Individual evidence
- ↑ ^{a } ^{b } ^{c} DIN 5493: 2013-10: Logarithmic quantities and units
- ↑ ^{a } ^{b } ^{c} DIN EN 60027-3: 2007-11: Symbols for electrical engineering - Part 3: Logarithmic and related quantities and their units