Neper

The neper (symbol: Np) is a logarithmic unit for ratios of measurements of physical field and power quantities, such as gain and loss of electronic signals.As is the case for the decibel and bel, the neper is a unit defined in the international standard ISO 80000.The level of a ratio of two signal amplitudes or root-power quantities, with the unit neper, is given by[2] where[3] The neper is defined in terms of ratios of field quantities — also called root-power quantities — (for example, voltage or current amplitudes in electrical circuits, or pressure in acoustics), whereas the decibel was originally defined in terms of power ratios.A power ratio 10 log r dB is equivalent to a field-quantity ratio 20 log r dB, since power in a linear system is proportional to the square (Joule's laws) of the amplitude.
John Napier after whom the unit is named
Mirifici logarithmorum canonis constructi o, 1825
Neper (disambiguation)John Napierlogarithmic unitratiosfield and power quantitiesdecibelinternational standardISO 80000International System of Unitslogarithmic scalelogarithmnatural logarithmEuler's numberroot-power quantitiespower quantitiesInternational System of QuantitiesLevel (logarithmic quantity)voltagecurrentpressureacousticsJoule's lawsInternational Telecommunication Unioncoherentrelative differencelog pointNat (unit)Nepers per metreInternational Bureau of Weights and MeasuresIEC 60027-3IEEE Journal of Oceanic EngineeringSI unitsBase unitsamperecandelakelvinkilogramsecondDerived units with special namesbecquerelcoulombdegree CelsiusnewtonpascalradiansiemenssievertsteradianOther accepted unitsastronomical unitdaltondegree of arcelectronvolthectareminuteminute and second of arcConversion of unitsMetric prefixesHistorical definitions of the SI base units2019 revision of the SISystem of units of measurement