define resistivity .explain the factors on which resistance of conductor depends
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Answer:
Resistivity is a measure of the resistance of a given size of a specific material to electrical conduction.
Resistivity may also be referred to as the specific electrical resistance, or volume resistivity, although these terms are less widely used.
Although materials resist the flow of electrical current, some are better at conducting it than others.The resistivity is a figure that enables comparisons of the way in which different materials allow or resist current flow.
To enable resistivity figures to be meaningful, specific units are used for resistivity, and there are formulas for calculating it and relating it to the resistance in Ohms for a given size of material.
Materials that conduct electrical current easily are called conductors and have a low resistivity. Those that do not conduct electricity easily are called insulators and these materials have a high 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.
The resistance of some materials decreases tremendously with a decrease in temperature in the very low temperature range of the order of absolute zero. Such substances are called superconductors.
Conductivity is the reciprocal of resistivity, and determines the ability of a material to conduct electric current.