5520A
Operators Manual
A-6
repeatability
The degree of agreement among independent measurements of a quantity under the same
conditions.
resistance
A property of a conductor that determines the amount of current that will flow when a
given amount of voltage exists across the conductor. Resistance is measured in ohms.
One ohm is the resistance through which one volt of potential will cause one ampere of
current to flow.
resolution
The smallest change in quantity that can be detected by a measurement system or device.
For a given parameter, resolution is the smallest increment that can be measured,
generated, or displayed.
rf (radio frequency)
The frequency range of radio waves; 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 (i.e.,
power); therefore, they sense true rms voltage.
resistance temperature detector (RTD)
A resistance device that provides a proportional resistance output for a temperature of
the device. Most RTDs are characterized by their resistance at 0 °C, called the ice point.
The most common ice point is 100 Ω at 0 °C. The curve of resistance vs. temperature
can be one of several: pt385 (0.00385 ohms/ohm/°C) and pt3926 (0.003926
ohms/ohm/°C) are examples.
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 0V with 0V applied, but something other than 10V with 10V 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.”
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