A parallel plate capacitor with plate area A and separation between the plates d is charged by a constant current I. Consider a plane surface of area $\frac{A}{3}$ parallel to the plates and drawn symmetrically between the plates. The displacement current through this area is:

$\frac{I}{3}$

The displacement current = conduction current = I corresponding to area A. Therefore displacement current for area $\frac{A}{3}$ is $\frac{I}{3}$.