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Resistivity

Question:
I know that the resistivity of an insulating paper is 10x109 Wm.
But how do I set up an experiment to find out the resistivity or to prove it is correct or not ?

Answer:

The paper that you have apparently has a resistivity of 10x109Wm or 10000 MWm.

Lets also assume that you have a digital meter that will enable you to measure a resistance of around 10 MW. (this is quite normal for the meters available in Britain now).

The connection between resistance and resistivity is:

Resistance = resistivity x length/area.
Now if the resistance is 107 W, the resistivity 1010 Wm and the paper is 10-4 m thick then you would need a piece 0.1 square metres in area with contacts taped to the two faces. Possible!

Alternatively using a pico ammeter (currents as low as 10-10 A. You could tape the contacts to the two faces and simply measure the current passing through the paper with a variety of applied voltages.

So for a piece of your paper 1 cm square with a resistance of 1010W the current for a 12V input would be 12/1010 = 1.2 nA (12x10-10 A) easily within the range of the meter I have looked at.

 
 
 
© Keith Gibbs 2011