Lake Shore Model 370 AC Resistance Bridge User’s Manual
resolution
. The degree to which nearly equal values of a quantity can be discriminated.
2
display resolution
. The resolution of the physical display of an instrument. This is not always the same as the measurement
resolution of the instrument. Decimal display resolution specified as "
n
digits" has 10
n
possible display values. A resolution of
n
and one-half digits has 2
×
10
n
possible values.
measurement resolution
. The ability of an instrument to resolve a measured quantity. For digital instrumentation this is often
defined by the analog to digital converter being used. A n-bit converter can resolve one part in 2
n
. The smallest signal change that
can be measured is the full scale input divided by 2
n
for any given range. Resolution should not be confused with accuracy.
RhFe
. Rhodium-iron. Rhodium alloyed with less than one atomic percent iron is used to make the Lake Shore RF family of sensors.
Rhodium-iron is a spin fluctuation alloy which has a significant temperature coefficient of resistance below 20 K where most metals
rapidly lose sensitivity.
Roman numerals
. Letters employed in the ancient Roman system of numeration as follows:
I
1 VI
6 L
50
II
2 VII
7 C
100
III
3 VIII
8 D
500
IV 4
IX 9
M
1000
V 5
X 10
root mean square (RMS)
. The square root of the time average of the square of a quantity; for a periodic quantity the average is taken
over one complete cycle. Also known as effective value.
1
RS-232C
. Bi-directional computer serial interface standard defined by the Electronic Industries Association (EIA). The interface is
single-ended and non-addressable.
Seebeck effect
. The development of a voltage due to differences in temperature between two junctions of dissimilar metals in the
same circuit.
1
self-heating
. Heating of a device due to dissipation of power resulting from the excitation applied to the device. The output signal
from a sensor increases with excitation level, but so does the self-heating and the associated temperature measurement error.
sensitivity
. The ratio of the response or change induced in the output to a stimulus or change in the input. Temperature sensitivity of a
resistance temperature detector is expressed as S = dR/dT.
setpoint
. The value selected to be maintained by an automatic controller.
1
serial interface
. A computer interface where information is transferred one bit at a time rather than one byte (character) at a time as in
a parallel interface. RS-232C is the most common serial interface.
SI
. Système International d'Unités.
See
International System of Units.
stability
. The ability of an instrument or sensor to maintain a constant output given a constant input.
still
. A device used to evaporate liquids; heat is applied to the liquid, and the resulting vapor is condensed to a liquid state.
1
strain relief
. A predetermined amount of slack to relieve tension in component or lead wires. Also called stress relief.
superconducting magnet
. An electromagnet whose coils are made of a type II superconductor with a high transition temperature and
extremely high critical field, such as niobium-tin, Nb
3
Sn; it is capable of generating magnetic fields of 100,000 oersteds and more
with no steady power dissipation.
1
See
electromagnet.
susceptance
. In electrical terms, susceptance is defined as the reciprocal of reactance and the imaginary part of the complex
representation of admittance: [suscept(ibility) + (conduct)ance].
susceptibility (
χ
)
. Parameter giving an indication of the response of a material to an applied magnetic field. The susceptibility is the
ratio of the magnetization (M) to the applied field (H).
χ
= M/H. In both SI units and cgs units the volume susceptibility is a
dimensionless parameter. Multiply the cgs susceptibility by 4
π
to yield the SI susceptibility.
See
also Initial Susceptibility and
Differential Susceptibility. As in the case of magnetization, the susceptibility is often seen expressed as a mass susceptibility or a
molar susceptibility depending upon how M is expressed.
temperature scales
.
See
Kelvin Scale, Celsius Scale, and ITS-90. Proper metric usage requires that only Kelvin and degrees Celsius
be used. However, since degrees Fahrenheit is in such common use, all three scales are delineated as follows:
Boiling point of water
Freezing point of water
Absolute zero
kelvin
Celsius
Fahrenheit
0 K
273.15 K
373.15 K
–273.15 °C
0 °C
100 °C
–459.67 °F
32 °F
212 °F
Triple point of water
273.16 K
To convert Kelvin to Celsius, subtract 273.15.
To convert Celsius to Fahrenheit: multiply °C by 1.8 then add 32, or: °F = (1.8 × °C) + 32.
To convert Fahrenheit to Celsius: subtract 32 from °F then divide by 1.8, or: °C = (°F – 32 )/1.8.
temperature coefficient, measurement
. The measurement accuracy of an instrument is affected by changes in ambient temperature.
The error is specified as an amount of change (usually in percent) for every one degree change in ambient temperature.
tesla (T)
. The SI unit for magnetic flux density (B). 1 tesla = 10
4
gauss
Glossary of Terminology
A-7
