Electric current: The current through a given medium is defined as
charge passing through the medium per unit time. It is a scalar, that is –
I
=dQ/dt Ampere.
Types of current: Current is of three types-
Convection current: It is defined as the current produced by a beam of electrons flowing through an insulating medium. This doesn’t obey Ohm’s law. For example, current through a vacuum, liquid and so on is convection current.
Conduction current: It is defined as the current produced due to flow of electrons in a conductor. This obeys Ohm’s law. For example, current in a conductor like copper is conduction current.
Displacement current: It is defined as the current which flows as a result of time-varying electric field in a dielectric material. For example, current through a capacitor when a time-varying voltage applied is displacement current.
