The displacement current in Maxwell's equations arises from:

Solution

Physics sir · 3 steps

Displacement current is Maxwell's name for a changing electric flux, not for any charge that moves.

1. The gap problem. While a capacitor charges, conduction current I flows in the wires but no charge crosses the gap between the plates. Ampere's law alone would then give two different answers for the magnetic field, depending on which surface you choose.
2. Maxwell's fix. In the gap the electric field grows as charge builds up on the plates, so the electric flux Φ_E through the gap changes. Maxwell added a term for this changing flux, and it carries exactly the same current I across the gap.

   I_d = ε₀ dΦ_E/dt

3. So. Displacement current comes from the changing electric flux, option (b). With it, the current is the same everywhere in the circuit and the magnetic field is the same whichever surface you choose.

The idea to keep. A changing electric field makes a magnetic field, just as a real current does. Whenever you see ε₀ dΦ_E/dt, think displacement current.

Answer from the NTA final answer key. Solution by PrepWiser.