what is displacement current????
what is conduction current???
Conduction current is the electric current that flows through a conductor because of an applied potential difference.
Displacement current appears as a theoretical necessity in situations where non steady current is encountered. Suppose let us consider a charging capacitor (not has been completely charged yet) consisting of parallel plates as shown in the figure. Now it has been found that if we keep a magnetic needle between the plates it will shows a deflection indicating that there exists a magnetic field between plates.
Now according to Ampere circuital law there must exists a current flow to have a magnetic field according to the relation:
---1.
But between the plates there exists no conduction current, thus the contour C1 encloses no current thus.
---2.
Again, applying Ampere circuital law in contour C2 gives
---3.
But eqn. 1 and eqn. 2 gives a contradiction.
Thus to resolve the contradiction Maxwell proposed that Ampere circuital should be modified and an invisible current is to be considered that gives rise to a magnetic field between the capacitor plates. Thus, Ampere-Maxwell law became
---4.
Maxwell argued that the electric field is changed between the plates due to mounting charge on the plates and a changing electric field gives rise to a magnetic field.
Thus displacement current is the current that is included to explain the magnetic field inside the capacitor due to mounting up of charges on its plates.
Mathematically,