Answer: Inductor.
- A Capacitor
- B Resistor
- C External source
- D Inductor
Correct answer: D. Inductor
Explanation: Energy oscillates between the capacitor and inductor. Starting with maximum capacitor energy, after T/4 the capacitor energy becomes zero and the inductor has maximum energy.
In a pure inductor the current lags the voltage by 90° (energy is briefly stored in the magnetic field before current responds); in a pure capacitor the current leads the voltage by 90° (current must flow to build up charge before voltage rises) - the mnemonic "ELI the ICE man" keeps these straight.
Concept context
AC circuits, impedance, LCR series circuit, resonance, transformers, and power factor.