Answer to Question #231075 in Electricity and Magnetism for Sanjib Barik

Question

What is a linear conductor? Discuss the conditions under which a metal does not 

behave as a linear conductor.

Answer 1

We define the resistivity $\rho$ of a material as the ratio of the magnitudes of electric field E and current density J: $\rho = \frac{E}{J}$

A material that obeys Ohm’s law reasonably well is called an ohmic conductor or a linear conductor. For such materials, at a given temperature, $\rho$ is a constant that does not depend on the value of E. If the temperature changes the resistivity as well thus the material might not behave as a linear conductor. In devices that do not obey Ohm’s law, the relationship of voltage to current may not be a direct proportion, and it may be different for the two directions of current.

Reference:

• Sears, F. W., & Zemansky, M. W. (1973). University physics.