Question
Sat August 06, 2011 By:

how is resistence and resistivity disimmilar???

Expert Reply
Mon August 08, 2011
Apply a voltage V across a wire and measure the current. Divide V/I and by definition, that is its resistance. R=V/I
Resistivity is defined as the constant of proportionality in the formula
where l is the length of the wire and A its cross section area. is the resistivity. It's a property of the material. Because resistance in general depends on a number of things like length, cross section and temperature, resistivity enables you to compare the resistance of different materials by considering samples with the same length and cross section.
 
Resistance is the obstruction offered to the flow of current by a conductor.
Resistivity is the obstruction offered to the flow of current by UNIT AREA OF the conductor.

So basically, resistance is the property of the object (say a copper wire), whereas resistivity is the property of the substance (copper).

And so resistance depends upon the properties of the object.
Whereas resistivity depends upon the properties of the metal.

So for example take two objects A and B made of aluminium. Both are of a different size.
The resistance of A & B will be different.
But the resistivity will be the same.
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