When a capacitor is subjected to a D.C. source it takes small time interval to get fully charged up. During this small time interval there is no passage of charge through dielectric, yet we use a term - displacement current. This term is used because:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → There is a continuous change of electric field between plates and hence electric flux
Maxwell showed that a changing electric flux produces a magnetic field in the same way as a conduction current. He called the term the displacement current.
\( \displaystyle i_{d} = \varepsilon_0\,\frac{d\Phi_{E}}{dt} \)
While the capacitor charges, the charge on the plates grows, so the field between the plates and the flux through the gap keep changing. This changing flux carries the current across the gap, although no charge crosses the dielectric.
Option (1) There is a slow motion of charge from one plate to another — Incorrect. No charge moves through the dielectric from one plate to the other; the question itself says so.
Option (3) The electric charge from battery stops moving — Incorrect. During charging the charge from the battery is still flowing in the wires; it stops only when the capacitor is fully charged.
Option (4) There is temporary breakdown of dielectric — Incorrect. The displacement current needs no breakdown of the dielectric.
NCERT (2026-27):
Displacement Current – “… The source of a magnetic field is not just the conduction electric current due to flowing charges, but also the time rate of change of electric field.”
Displacement Current – “… On the other hand, inside the capacitor, there is no conduction current, i.e., ic = 0, and there is only displacement current, so that id = i.”