Maxwell argued that a changing electric field between the capacitor plates must induce a magnetic field. As currents are the usual sources of magnetic fields, a changing electric field must be associated with a current. Maxwell called this current as the displacement current.
If ‘A’ be the area of the capacitor plates and ‘cf be the charge on the plates at any instant ‘f during the charging process, then the electric field in the gap will be
But \(\frac{dq}{dt}\) is the rate of change of charge on the capacitor plates. it is called displacement current and given by
Id = \(\frac{dq}{dt}\) - ε0\(\frac{dΦ_E}{dt}\)
This is the missing term in Ampere’s Circuital Law. The total current must be the sum of the conduction current Ic Hence, the modified form of the ampere’s law.
