Question

With some initial change at \(t = 0^+\), a capacitor will act as ________.

• A. Open circuit
• B. Short circuit
• C. A current source
• D. A voltage source

Hint:

At \(t = 0^+\), capacitor behaves like a short circuit; at steady state (DC), it behaves like an open circuit.

Answer 1

The Correct Option is B

At the moment of switching (\(t = 0^+\)), a capacitor cannot change its voltage instantaneously because: \[ i_C = C \frac{dv}{dt} \] If there's an abrupt change in voltage, it would require infinite current, which is not physically possible. Instead, the capacitor behaves like a short circuit at \(t = 0^+\), allowing a surge of current as it charges or discharges.
As time progresses, the capacitor charges and gradually acts more like an open circuit in DC conditions. Final Answer: (2) Short circuit