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true value
Also called legal value, the accepted, consensus, (for example, the correct value of the
quantity being measured).
uncertainty
The maximum difference between the accepted, consensus, or true value and the
measured value of a quantity. Uncertainty is normally expressed in units of ppm (parts
per million) or as a percentage. (Accuracy is the same as 1 - % uncertainty.)
units
Symbols or names that define the measured quantities. Examples of units are: V, mV, A,
kW, and dBm. See also "SI System of Units."
volt
The unit of emf (electromotive force) or electrical potential in the SI system of units. One
volt is the difference of electrical potential between two points on a conductor carrying
one ampere of current, when the power being dissipated between these two points is
equal to one watt.
watt
The unit of power in the SI system of units. One watt is the power required to do work at
the rate of one joule/second. In terms of volts and ohms, one watt is the power dissipated
by one ampere flowing through a 1Ω load.
wideband
AC voltage at frequencies up to and including the radio frequency spectrum.
verification
Checking the functional performance and uncertainty of an instrument or standard
without making adjustments to it or changing its calibration constants.
voltage guard
A floating shield around voltage measurement circuitry inside an instrument. The voltage
guard provides a low-impedance path to ground for common-mode noise and ground
currents, thereby eliminating errors introduced by such interference.
working standard
A standard that is used in routine calibration and comparison procedures in the
laboratory, and is maintained by comparison to reference standards.
zero error
Same as offset error. The reading shown on a meter when an input value of zero is
applied is its zero or offset error.
C
Appendices
Glossary
C-9
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