What happens when you connect a charged capacitor with an inductor?

What happens when you connect a charged capacitor with an inductor?

• A. The capacitor and inductor exchange energy, causing the circuit to oscillate
• B. The capacitor immediately discharges and stops
• C. The inductor absorbs all energy and becomes a short circuit
• D. The circuit becomes a pure resistor

Answer: (A)

When you connect a charged capacitor to an inductor, you set up an LC circuit where energy moves back and forth between the capacitor’s electric field and the inductor’s magnetic field. The capacitor starts with electrical energy that creates a current flow through the inductor. as this current flows, the capacitor’s stored energy decreases while the inductor stores energy in its magnetic field. When the capacitor voltage reaches zero, all the energy is in the inductor, and the current continues to flow, charging the capacitor with opposite polarity, so the energy swings back again. This back-and-forth transfer causes oscillations in current and voltage at a natural frequency f = 1/(2π√(LC)). In an ideal circuit with no resistance, the oscillation would continue indefinitely; with any resistance, it would gradually dampen. The other ideas don’t fit because the energy doesn’t disappear instantly, the inductor doesn’t simply absorb all energy to become a short, and a circuit with only an inductor and capacitor isn’t a pure resistor—the defining behavior is the continuous exchange of energy between the two reactive elements.

When you connect a charged capacitor to an inductor, you set up an LC circuit where energy moves back and forth between the capacitor’s electric field and the inductor’s magnetic field. The capacitor starts with electrical energy that creates a current flow through the inductor. as this current flows, the capacitor’s stored energy decreases while the inductor stores energy in its magnetic field. When the capacitor voltage reaches zero, all the energy is in the inductor, and the current continues to flow, charging the capacitor with opposite polarity, so the energy swings back again. This back-and-forth transfer causes oscillations in current and voltage at a natural frequency f = 1/(2π√(LC)). In an ideal circuit with no resistance, the oscillation would continue indefinitely; with any resistance, it would gradually dampen.

The other ideas don’t fit because the energy doesn’t disappear instantly, the inductor doesn’t simply absorb all energy to become a short, and a circuit with only an inductor and capacitor isn’t a pure resistor—the defining behavior is the continuous exchange of energy between the two reactive elements.