Answer: Mechanical energy to electrical energy using electromagnetic induction.
- A Mechanical energy to electrical energy using electromagnetic induction
- B Electrical energy back into mechanical energy, like a motor
- C Direct current into alternating current, like an inverter circuit
- D Thermal energy directly into electrical energy, like a thermocouple
Correct answer: A. Mechanical energy to electrical energy using electromagnetic induction
Explanation: An AC generator (alternator) uses electromagnetic induction (Faraday's law) to convert mechanical rotation into AC electrical energy. A coil rotates in a magnetic field.
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.