Appendices
Glossary C
C-7
rf (radio frequency)
The frequency range of radio waves; ranging from 150 kHz up to the infrared range.
rms (root-mean-square)
The value assigned to an ac voltage or current that results in the same power dissipation
in a resistance as a dc current or voltage of the same value.
rms sensor
A device that converts ac voltage to dc voltage with great accuracy. RMS sensors operate
by measuring the heat generated by a voltage through a known resistance (for example,
power); therefore, they sense true rms voltage.
scale
The absolute span of the reading range of a measurement device including overrange
capability.
scale error
Same as gain error. Scale or gain error results when the slope of the meter’s response
curve is not exactly 1. A meter with only scale error (no offset or linearity error), will
read 0 V with 0 V applied, but something other than 10 V with 10 V applied.
secondary standard
A standard maintained by comparison against a primary standard.
sensitivity
The degree of response of a measuring device to the change in input quantity, or a figure
of merit that expresses the ability of a measurement system or device to respond to an
input quantity.
shield
A grounded covering device designed to protect a circuit or cable from electromagnetic
interference.
SI System of Units
The accepted International System of Units. See also “units”, “base units”, and “derived
units.”
stability
A measure of the freedom from drift in value over time and over changes in other
variables such as temperature. Note that stability is not the same as uncertainty.
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