What is resistivity?
The resistivity of a material is the resistance of a wire of that material of unit length and unit cross-sectional area. The unit for resistivity is the ohm-metre.
The resistivity of a material depends on its nature and the temperature of the conductor, but not on its shape and size.
A good conductor has less resistivity, whereas a bad conductor or insulator has high resistivity.
The resistivity of semi-conductors lies between that of conductors and insulators. The resistivity of a metallic conductor increases with an increase in its temperature, whereas the resistivity of a semi-conductor decreases with an increase in its temperature.