An AC generator differs from a DC generator by having:

Both AC (Alternating Current) and DC (Direct Current) generators operate on the principle of electromagnetic induction, described by Faraday's Law: $$\varepsilon = -N \frac{\Delta \Phi}{\Delta t}$$ As a coil rotates within a uniform magnetic field, the magnetic flux $\Phi = BA \cos(\theta)$ changes sinusoidally. This means that the current induced *inside* the rotating coil of both types of generators is inherently alternating. The fundamental difference lies in how this current is collected and delivered to an external circuit: 1. **AC Generator (Alternator):** Uses **slip rings**. Each end of the rotating coil is connected to a complete, continuous metal ring. As the coil flips polarity, the rings stay connected to the same ends, allowing the external current to alternate direction. 2. **DC Generator:** Uses a **split-ring commutator**. This is a single ring cut into segments. It acts as a mechanical rectifier, flipping the connection every half-turn so that the current in the external circuit always flows in one direction. Therefore, the AC generator differs from the DC generator specifically by having slip rings instead of a split commutator.