The interaction between capacitance and frequency is governed by capacitive reactance, represented as XC. Reactance is the opposition to AC flow. For a capacitor: where: Capacitive reactance XC is inversely proportional to frequency f. As frequency increases, reactance decreases, allowing more AC to flow through the capacitor.
As frequency increases, reactance decreases, allowing more AC to flow through the capacitor. At lower frequencies, reactance is larger, impeding current flow, so the capacitor charges and discharges slowly. At higher frequencies, reactance is smaller, so the capacitor charges and discharges rapidly.
Answer: As frequency increases, capacitive reactance decreases, reducing capacitor impedance, and allowing more AC to flow. In summary, capacitance and frequency have an inverse relationship governed by capacitive reactance.
Capacitive reactance of a capacitor decreases as the frequency across its plates increases. Therefore, capacitive reactance is inversely proportional to frequency. Capacitive reactance opposes current flow but the electrostatic charge on the plates (its AC capacitance value) remains constant.
It is easy to prove why capacitive reactance decreases with increased capacitance. The more we increase the capacitance of a capacitor -> for the same charge at the plates of the capacitor we get less voltage which resists current from the AC source. But why is reactance decreased with the increase of the frequency of the applied signal?
However, as the operating frequency approaches the capacitor’s self-resonant frequency, the capacitance value will appear toincrease, resulting in an effective capacitance (C E) that is larger than the nominal capacitance. This article will address the details of effective capacitance as a function of the application operating frequency.