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Resistivity measurements of a circular shaped sample 
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#1
Nov1112, 09:07 PM

P: 4

Hai,
I am doing my masters degree in physics. can somebody help me in which formula to use for calculating resistivity of a sample of circular shape using two probe measurements, which should include thickness and correction factor also. Thank You!!! 


#2
Nov1112, 10:09 PM

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P: 12,475

Welcome to PF;
You should be able to get the resistivity from a measurement of the DC resistance across the sample and it's geometry. Which direction you take the resistance measurement depends on the specifics of your samples shape. "circular shape" is a little vague. 


#3
Nov1512, 12:54 AM

P: 4

thanks for the reply...
I measured the dc resistance already,but how to calculate the resistivity for a circular sample. Using two probe method. 


#4
Nov1512, 02:27 AM

P: 5,462

Resistivity measurements of a circular shaped sample
It is usual to choose the measurement sample so that it is long compared to its cross sectional area (ie along a length of wire) so that the effect of the spread of current may be ignored. If you are measuring across a disk or ball shaped object then you will have to set up and solve the CoulombBousinesq equations, using your dimensions as boundary conditions. Hertz solved these in about 1885. However it is a three dimensional problem so you need to be clear as to the geometry. 


#5
Nov1512, 05:27 PM

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Still, I did try to prompt for this: Otherwise the best anyone can do is describe the 2probe method in general. 


#6
Nov2012, 02:27 AM

P: 4

i understood what you are trying to convey!!!
it is circular disk shaped sample of thickness of 1mm or so. The resistivity of the sample is very high, so we preferred to measure using two probe method. There are formulas for vanderpauw, collinear four probe configurations to calculate the resistivity from the measured voltage. Similarly i need a formula for two probe configuration to calculate the resistivity of circular disk shaped sample. 


#7
Nov2012, 02:57 AM

P: 5,462

You still didn't answer the question about the geometry.



#8
Nov2412, 01:55 AM

P: 4

it is circular pellet of thickness 0.6mm and diameter 13mm.



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