Measured Surface Resistivity Much Higher than Theoretical Value (Why?)

[LulaBell]

I recently conducted a physics lab to measure the surface resistivity of a conductive sheet of a paper with a carbon filler. The theoretical Rs is approx. 5,000 Ω/☐ for this paper and yet we have calculated two Rs values:

Rs when Varying Length and holding Width = 10100 +/- 83.07 Ω/☐
Rs when Varying Width and holding Length = 11220 +/- 63.02 Ω/☐

To me, this discrepancy is very large, and I can't seem to explain why it could even occur, although we are not the only ones measuring this almost double Rs, it seems consistent around 10,000 Ω/☐ across the entire lab and yet I can't figure out why that is. Does it have something to do with the flow of electrons being blocked? Perhaps we did not connect something right although I struggle to see how that would be consistent with other groups.

Any help is very appreciated.

 

[scottdave]

So what measurement procedures did you use? How does your setup method compare to how the paper is typically used in practice?

 

[kuruman]

Yes the procedures that you followed are important. Also, what do you mean by "theoretical" resistivity? Do you know the model that has been used to calculate it? There might be a factor of 2 in the calculation (and the measurement) that was made to determine it vis-à-vis the way you conducted and analyzed your measurement. Remember that a sheet of paper has two surfaces.

 

[scottdave]

Do you have any additional details that may be useful @LulaBell ?

Or were you able to resolve the discrepancy?