Question

In case of conductors and insulators, if an electric field is applied then conduction current density $\vec{J}$ is:
A. in the direction of electron flow.
B. in the direction of proton flow.
C. in the direction of electric field.
D. against the direction of the electric field.

Answer 1

Conduction current is the current produced in a conductor due to electrons' flow at a uniform rate. In other words, we can say that it is the current in an electric conductor when the electric field doesn't vary with time. Conduction current density is the value of conduction current per unit area of that conductor.

Complete step by step answer:
The direction of the flow of conduction current is the same as the direction of protons' flow. We know that the direction of the electric field is also in the direction of the flow of protons. We can write the expression for conduction current density as below:
$\vec{J}$ = ${\dfrac{I}{A}}$
Here I is conduction current, and A is the area of flow of current.
As current density is directly proportional to the conduction current, we can say that current density is in the direction of the conduction current.
Therefore, in the case of conductors and insulators, conduction current density is in the direction of proton and electric field flow.

So, the correct answers are “Options B and C”.

Note: Electric conductors are those materials that allow the transportation of charge in one or than one directions. Mainly, metals are termed as electrical conductors. The conduction current is mainly carried due to the flow of electrons as in conductors, there is a sea of free electrons, resulting in current flow. Whereas insulators are those materials in which flow of charge is not allowed as current-carrying charges are absent.