A parallel-plate capacitor is being charged by a conduction current I. Neglect leakage. The displacement current between the capacitor plates is:
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Question

A parallel-plate capacitor is being charged by a conduction current I. Neglect leakage. The displacement current between the capacitor plates is:

G1 Physics · Accepted Answer

Maxwell introduced displacement current so that current continuity is maintained in a charging capacitor. Displacement current is I = ε₀ dΦₑ/dt. For parallel plates with uniform electric field, Φₑ = EA. Also, E = Q/(ε₀A). Hence, Φₑ = [Q/(ε₀A)]A = Q/ε₀. Therefore, I = ε₀ d(Q/ε₀)/dt = dQ/dt. But dQ/dt is the conduction current in the connecting wire. Hence the displacement current between the plates is equal in magnitude to the conduction current. Correct option: B.