• word_count: 200

The AC generator converts mechanical rotation into alternating electrical energy. A coil of $N$ turns, area $A$, rotates at angular velocity $\omega$ in uniform field $B$. The flux varies as $\Phi = NBA\cos\omega t$, and the induced EMF is $\varepsilon = NBA\omega\sin\omega t = \varepsilon_0\sin\omega t$.

Key features: peak EMF $\varepsilon_0 = NBA\omega$ (proportional to turns, field, area, and frequency). The EMF is maximum when the coil plane is parallel to $\vec{B}$ (flux = 0, rate of change maximum). The EMF is zero when perpendicular to $\vec{B}$ (flux maximum, rate of change zero). The frequency of the output equals the rotation frequency: $f = \omega/(2\pi)$.

RMS values for power calculations: $\varepsilon_{\text{rms}} = \varepsilon_0/\sqrt{2}$, $I_{\text{rms}} = I_0/\sqrt{2}$. The AC generator uses slip rings for continuous contact. A DC generator uses a split-ring commutator to rectify the output.

The Faraday disc (homopolar generator) — a rotating conducting disc — produces constant DC: $\varepsilon = B\omega R^2/2$. Unlike the coil generator where flux alternates, the disc always sweeps area in the same sense.