AC generator
A device that converts mechanical energy into alternating current (AC) electrical energy. A coil rotates in a uniform magnetic field; the changing magnetic flux induces an AC voltage V = NBA ω sin(ωt) where ω is angular frequency.
Formula
EMF = NBAω sin(ωt)
Real World
The turbines at Drax power station in Yorkshire are essentially giant AC generators — steam spins coils inside magnetic fields at 50 revolutions per second, directly producing the 50 Hz mains frequency used in UK homes.
Exam Focus
Peak EMF occurs at sin(ωt) = 1 (coil parallel to field); zero EMF at cos(ωt) = 0 (coil perpendicular) — mixing these up is the most common error.
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