Lake Shore 460, User Manual

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Lake Shore Model 460 Gaussmeter User’s Manual
Glossary of Terminology A-5
ppm . Parts per million, e.g., 4 x 10
–6
is four parts per million.
precision . Careful measurement under controlled conditions which can be repeated with similar results. See repeatability.
Also means that small differences can be detected and measured with confidence. See resolution.
prefixes . SI prefixes used throughout this manual are as follows:
Factor Prefix Symbol
10 24
yotta
Y
10
21
zetta Z
10 18 exa E
10 15 peta P
10 12 tera T
10
9
giga G
10 6 mega M
10 3 kilo k
10 2 hecto h
10
1
deka da
Factor Prefix Symbol
10 –1 deci d
10
–2
centi c
10 –3 milli m
10 –6 micro µ
10 –9 nano n
10
–12
pico p
10 –15 femto f
10 –18 atto a
10 –21 zepto z
10
–24
yocto y
probe . A long, thin body containing a sensing element which can be inserted into a system in order to make
measurements. Typically, the measurement is localized to the region near the tip of the probe.
remanence . The remaining magnetic induction in a magnetic material when the material is first saturated and then the
applied field is reduced to zero. The remanence would be the upper limit to values for the remanent induction. Note that
no strict convention exists for the use of remanent induction and remanence and in some contexts the two terms may
be used interchangeably.
remanent induction . The remaining magnetic induction in a magnetic material after an applied field is reduced to zero.
Also see remanence.
repeatability . The closeness of agreement among repeated measurements of the same variable under the same
conditions.
2
resolution . The degree to which nearly equal values of a quantity can be discriminated.
2
display resolution . The resolution of an instrument's physical display. 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 x 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.
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.
scalar . A quantity which has magnitude only and no direction, in contrast to a vector.
1
semiconducting material . A conducting medium in which the conduction is by electrons, and holes, and whose
temperature coefficient of resistivity is negative over some temperature range below the melting point.
2
semiconductor . An electronic conductor, with resistivity in the range between metals and insulators, in which the electric
charge carrier concentration increases with increasing temperature over some temperature range. Note: Certain
semiconductors possess two types of carriers, namely, negative electrons and positive holes.
2
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 a 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.
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.