Ohmic Materials


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The ohmic materials are those which obey Ohm’s law. These are basically the good conductors of electricity so that the current flowing inside these conductors is always proportional to the resistance of them.

Ohm’s law states that for Ohmic materials the ratio of the current density to the electric field is a constant σ that is independent of the electric field producing the current. The current density is given by,

J = nQvd ≡ I/A

Here I = current flowing in the conductor, A = cross sectional area of the conductor, vd is the drift velocity of the electrons flowing in the conductor and n = number of mobile charge carriers present in the conductor, Q = charge on each carrier in the conductor. Now the Ohm’s law is given by,

J = σE

When an insulator is placed in an electric field whether in a static condition or in dynamic condition, there will be no flow of electric current since there is lack of energy content in the electric charges present in the insulator and also there is lack of number of charge carriers. Thus, it is not conducive for the flow of charge in the insulator.