The charge on a parallel plate capacitor is varying as q = q0 sin 2πnt The plates are very large and close together. Neglecting the edge effects, the displacement current through the capacitor is:

$\frac{q}{\varepsilon_0 A}$ $\frac{q_0}{\varepsilon_0} \sin 2 \pi n t$ $2 \pi n q_0 \cos \pi n t$ $\frac{2 \pi n q_0}{\varepsilon_0} \cos 2 \pi nt$

$2 \pi n q_0 \cos \pi n t$

$I_D= \frac{dq}{dt}=\frac{d}{dt} q_0 \sin 2 \pi nt=2 \pi nq_0 \cos 2 \pi q_0 \cos 2 \pi nt$