• AC generators date back to the 1830s.
• They are commonly used today and involve a coil rotating relative to a magnetic field.

• Imagine a fixed coil between the poles of a U-shaped magnet.
• The coil rotates due to a turntable.
• Flux linkage to the coil varies depending on the coil's position.
• The coil links maximum flux when perpendicular to the magnetic field and minimum flux when parallel.

Real-world Example: Think of a Ferris wheel. At the bottom and top, you experience max and min thrill respectively. Similarly, the coil experiences max and min flux.

• A coil moving between zero and maximum flux twice every cycle results in a sine curve for flux linkage.
• Induced emf = negative rate of change of flux linkage.
• If flux linkage changes rapidly, the emf magnitude is highest.
• Induced emf graph resembles a negative cosine curve.

Real-world Example: The faster you push a swing (rate of change), the higher it goes (higher emf).

• Speed of turntable alters frequency and amplitude of emf.
• More coil turns or a bigger coil increases emf amplitude, but frequency remains unchanged if the turntable's speed is constant.

• Some have rotating magnetic fields, others have fixed magnets and rotating coils.
• The coil's direction of current flow changes based on its position relative to the magnetic field.