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7
• Why run an electrode to infinity when we can use it?
source
sink
P
V
source
=
i
ρ
2
π
r
source
r
source
sink
k
sin
r
2
i
V
π
ρ
=
r
sink
Total Voltage at P:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
−
π
ρ
=
−
=
ink
s
source
k
sin
source
p
r
1
r
1
2
i
V
V
V
Two Current Electrodes: Source and Sink
Can’t measure potential at single point unless the other end of our
volt meter is at infinity. This is inconvenient.
It is easier to
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Unformatted text preview: measure potential difference ( ∆ V) . This lead to use of four electrode array for each measurement. Measurement Practicalities Resulting measurement given as ∆ V=V P1V P2 = ρ I/(2 π )*(1/r 11/r 21/r 3 +1/r 4 ). Can be rewritten ∆ V= ρ I*G/(2 π ) where G/2 π is the Geometrical Factor of the array. ρ...
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This note was uploaded on 01/07/2012 for the course PHYSICS 384 taught by Professor Wei during the Spring '09 term at SUNY Stony Brook.
 Spring '09
 wei
 Current

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