Question
Mon May 16, 2011 By:
Dear sir,
I am unable to understand the concept of resistivity as well as the difference between resistivity and resistance.Kindly explain me.
Regards,
Sharmistha Panda
class 10 B

Explain me the definition of resistivity & the difference between resistance and resistivity.

Expert Reply
Mon May 16, 2011
Resistivity and resistance of a conductor are two diff. things. Resistance is the opposition to the flow of electrons (i.e., electrical current). Every substance has a certain amount of resistance. Resistance is measured in Ohms.

Resistivity is defined as the measure of the resistance a material imposes on current flow.   
The resistance of a given length of conductor depends upon the resistivity of that material,
the length of the conductor, and the cross-sectional area of the conductor,
R = r L /A
where R = resistance of conductor, 
 r = specific resistance or resistivity
L = length of conductor,
A = cross-sectional area of conductorThe resistivity (rho) allows different materials to be compared for resistance, according to their nature, without regard to length or area.   The higher the value of r, the higher the resistance.
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