In steady state, no current flows through a capacitor primarily because a capacitor is fully charged and has reached equilibrium with the applied voltage. Initially, when a voltage is applied across a capacitor, current flows as the capacitor charges. This charging process involves the movement of electrons onto one plate of the capacitor and away from the other plate. As the capacitor charges, the potential difference (voltage) across it increases until it equals the applied voltage. Once the capacitor reaches this steady state, the rate of charge on the capacitor plates becomes equal, resulting in no net flow of current through the capacitor. Essentially, in steady state, the capacitor acts as an open circuit to DC currents because it has stored an equal and opposite charge on each plate, preventing further current flow.
There is no current through a capacitor in steady state because the capacitor has completed its charging process. Initially, when a voltage is applied to a capacitor, current flows as the capacitor charges and the potential difference across its plates increases. However, as the capacitor charges, the current gradually decreases until it reaches zero when the capacitor is fully charged. At this point, the capacitor has stored maximum electrical potential energy in its electric field, and there is no longer any movement of charge or current through the capacitor. Thus, in steady state, the capacitor effectively blocks DC currents, behaving as an open circuit to the flow of electrons.
At steady state, a capacitor maintains a constant charge and voltage across its plates without allowing any current to pass through it. This state occurs once the capacitor has fully charged or discharged to the applied voltage. In practical circuits, this steady state is crucial for stabilizing voltage levels, filtering out unwanted frequencies, or storing electrical energy temporarily. Capacitors play a vital role in various applications, such as power supply filtering, timing circuits, and signal coupling, where their ability to hold charge and stabilize voltage is essential.
When a capacitor is fully charged in steady state, there is no current flow through it because the capacitor has stored maximum charge on its plates, resulting in equal and opposite charges on each plate. In this condition, the electric field between the plates is strong enough to maintain the voltage across the capacitor without the need for current flow. Because capacitors store energy in an electric field rather than conducting current through a physical path (like a resistor or wire), they effectively block DC current once fully charged. This property makes capacitors valuable in applications requiring energy storage, voltage regulation, or signal conditioning.
Capacitors cannot conduct current like a wire or resistor because they consist of two conductive plates separated by an insulating material (dielectric). When a voltage is applied across a capacitor, electrons accumulate on one plate (creating a negative charge) while an equal number of electrons are removed from the other plate (creating a positive charge). This accumulation of charge forms an electric field between the plates, which opposes further movement of charge carriers (electrons) once the capacitor is fully charged. As a result, while capacitors can initially conduct current during charging or discharging phases, they block direct current flow once they reach steady state because the electric field between the plates prevents any net flow of electrons through the capacitor.