Hioki RM2610, Инструкция по эксплуатации

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What is volume resistivity?
8.5 What is volume resistivity?
Volume resistivity is a physical property that indicates the comparative difficulty with which
electricity passes through a material. It is also known as resistivity, specific resistance, and
electrical resistivity. Volume resistivity is measured in [
Ω
m].
Each material has a characteristic volume resistivity that does not depend on its shape or size. As
a result, the characteristic offers a convenient means of comparing the electrical conductivity of
different materials.
The relationship between the volume resistivity ρ and the electrical resistance R is shown below.
[ R = ( V : Voltage drop) / ( I : Current)]
ρ = × R RCF
( V )·····(Equation 1)
Here
ρ = ×
R RCF
( V ) is a correction coefficient that corrects for the effects of the material’s shape, size,
and measurement position.
ρ = × R RCF
and
ρ = × R RCF
vary with the shape, size, and measurement position of
the material.
For example, for a columnar object with length L and cross-sectional area S , electrical resistance is
proportional to the length L and inversely proportional to the cross-sectional area S .
R
L
S
= ×
ρ
·····(Equation 2)
The proportionality coefficient here is the volume resistivity, and the equation can be changed as
shown below so that it can be compared with Equation 1.
ρ = × R S
L
····· (Equation 3)
Consequently, the object’s RCF can be expressed as follows:
RCF S
L
=
····· (Equation 4)
Methods for measuring the volume resistivity of a conductor include that described in JIS K 7194,
“Testing method for resistivity of conductive plastics with four-point probe array.”
Length ( L )
Width ( W )
Cross-sectional
area ( S )
Current (
I
)
DC power supply ( V )
Thickness ( t )
Resistance R
R v L
S
= ρ ρ
ρ
ρ
v L
tW
v
t
L
W
s L
W
= =
Volume resistivity ρν Surface resistance ρ s
R v L
S
= ρ
= Resistance
R
×
Cross-sectional area S
ρ
ρ
ρ v L
tW
v
t
L
W
s L
W
= =
=
Resistance
R
×
Width W
Length L Length L
ρ = × R RCF
( V )
ρ = × R RCF
( S)
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FA
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