According to the sources, capacitive reactance ($X_C$) is inversely proportional to the angular frequency ($\omega$) of the AC source, given by $X_C = 1/(\omega C)$ . When the operating frequency decreases, the capacitive reactance increases . The amplitude of the current in the circuit is $i_m = V_m / X_C = \omega C V_m$, which is directly proportional to the frequency . Therefore, a decrease in frequency leads to a decrease in the current flowing through the circuit. Since the conduction current is equal to the displacement current in a capacitor circuit, the displacement current also decreases.