Automotive Generator:  An automotive generator converts mechanical energy into electrical energy. This lightweight, high-performance machine generates electricity through electromagnetic induction. The generator is driven by means of a belt connected to the engine crankshaft pulley.

Operation: Voltage is induced into a conductor when a magnetic field is moved across the conductor. A simple example is a bar magnet with its magnetic field rotating inside a loop of wire (Refer to the illustration below). With the magnet rotating as indicated, the upper illustration shows the S pole of the magnet directly under the top loop and the N pole directly over the bottom loop. in this position, the induced voltage causes current to flow in the circuit from "A", through the load to "B". Since the current flows from positive to negative in the external circuit, the end of the wire loop marked "A" is positive and the end marked "B" is negative.

After the bar magnet rotates through one-half revolution (refer to the lower illustration), the N pole is directly under the top conductor and the S pole is directly over the bottom conductor. The induced voltage now causes current to flow in the opposite direction. The end of the loop marked "A" becomes negative polarity and the end marked "B" becomes positive. The polarity of the ends of the wire loop changed. After one complete revolution, the bar magnet is back where it started with "A" positive and "B" negative.

Consequently, current will flow through the load or external circuit first in one direction and then the other. This is an alternating current, which is developed internally by a generator. To be useful, this alternating current (AC) must be converted (rectified) to direct current (DC). This rectification is done with the use of diodes internal to the generator. Also internal to the generator is a voltage regulator to prevent excess voltage from damaging the 12-Volt automotive electrical system components.

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