What is the effect of a capacitor in a DC circuit after charging?

• A. It allows both AC and DC current to pass
• B. It blocks AC current
• C. It blocks DC current while allowing AC to pass
• D. It converts DC to AC current

Answer: (C)

A capacitor in a DC circuit serves a specific role after it has charged. Once the capacitor has reached its full charge, it effectively acts as an open circuit for DC current. This means it can no longer allow DC to flow through it. The primary effect of this charging process is that the capacitor stores electrical energy in the electric field created between its plates.

However, when it comes to AC currents, capacitors behave differently. They can charge and discharge rapidly with the alternating current, allowing AC to pass through while blocking any DC component. This property distinguishes capacitors in AC applications, where they are essential for filtering and coupling signals.

Therefore, in a DC context after charging, the capacitor will block any further DC current from flowing, while it has the ability to allow AC current to pass when presented with alternating signals.