In a DC steady-state for an RC circuit, what does the capacitor do?

In a DC steady-state for an RC circuit, what does the capacitor do?

• A. Discharges through the circuit
• B. Maintains a short circuit
• C. Passes DC without impedance
• D. It charges and becomes an open circuit

Answer: (D)

In DC steady state, a capacitor stops current flow because its voltage stops changing. The current through a capacitor is i = C dv/dt, so once dv/dt = 0, the current becomes zero. The capacitor has charged up to the supply (or the final node voltage) and, for DC, it presents an open path to current. That’s why the capacitor “charges and becomes an open circuit.” Initially it acts like a short, but after enough time it blocks DC current.

In DC steady state, a capacitor stops current flow because its voltage stops changing. The current through a capacitor is i = C dv/dt, so once dv/dt = 0, the current becomes zero. The capacitor has charged up to the supply (or the final node voltage) and, for DC, it presents an open path to current. That’s why the capacitor “charges and becomes an open circuit.” Initially it acts like a short, but after enough time it blocks DC current.