Final answer:
The alternator converts mechanical energy into electrical energy through electromagnetic induction, involving a coil within the electric generator rotating in a magnetic field to induce AC, which is then rectified to DC for use in cars. So, the correct option is b) electromagnetic induction
Step-by-step explanation:
The alternator converts mechanical energy into electrical energy by electromagnetic induction.
This is accomplished through the operation of an electric generator within the alternator, which comprises a coil rotating in a magnetic field. As the coil rotates, it cuts through the magnetic lines of force, thereby inducing an alternating current (AC) electromotive force (emf) in the coil. The generated AC voltage drives an AC current throughout the loops of the wire coil.
The alternator in cars is used to charge the battery and power the electrical system when the engine is running, and it is designed to produce direct current (DC) through the use of rectifiers.
Therefore, the correct option is b) electromagnetic induction