Displacement current is a concept in electromagnetism that was introduced to make Amperes circuit law logically consistent. It is defined as the rate of change of the electric displacement field (D) and is measured in Ampere. Displacement current arises due to varying electromotive force and is produced by a time-varying electric field rather than moving charges. It is a current that is produced by the rate of change of the electric displacement field and differs from the normal current that is produced by the motion of the electric charge. Displacement current has the same unit and effect on the magnetic field as conduction current depicted by Maxwells equation.

The Ampere-Maxwell equation includes displacement current and states that the line integral of the magnetic field around a closed loop is equal to the permeability of free space times the sum of the conduction current and the displacement current passing through the surface bounded by the loop. Displacement current plays a central role in the propagation of electromagnetic radiation, such as light and radio waves, through empty space.

Some characteristics of displacement current are:

• Displacement current does not appear from the actual movement of the electric charge as in the case of the conduction current but is produced by a time-changing electric field.
• Displacement current is the current in the insulated region of the charged capacitor due to the changing electric flux.
• Displacement current has the same unit as conduction current, i.e., Ampere (A) .

In summary, displacement current is a current due to the changing electric field and is defined as the rate of change of the electric displacement field. It was introduced to make Amperes circuit law logically consistent and plays a central role in the propagation of electromagnetic radiation.