A parallel plate capacitor is being charged by an external source by keeping the charging current fixed at a magnitude of 0.12 A. The magnitude of displacement current is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 0.12 A
Maxwell introduced the displacement current \( i_d = \varepsilon_0\,\frac{d\Phi_E}{dt} \) so that current is continuous through the gap of a charging capacitor. The charge on the plates is \( q = \varepsilon_0 E A = \varepsilon_0 \Phi_E \), so
\( \displaystyle i_d = \varepsilon_0\,\frac{d\Phi_E}{dt} = \frac{dq}{dt} = i_c \)
The displacement current between the plates is equal to the conduction current in the wires:
\( \displaystyle i_d = 0.12\,\mathrm{A} \)
NCERT (2026-27):
Displacement Current – “… In explicit terms, this means that outside the capacitor plates, we have only conduction current \( i_c = i \), and no displacement current, i.e., \( i_d = 0 \). On the other hand, inside the capacitor, there is no conduction current, i.e., \( i_c = 0 \), and there is only displacement current, so that \( i_d = i \).”