Final answer:
The advantage of a rotating magnetic field in an alternator is efficient AC power generation, dependent on rotation rate, number of coils, coil area, and magnetic field strength. Faster rotation rates increase the emf, demonstrating the feature of smooth and stable electrical output, akin to bicycle generators.
Step-by-step explanation:
The advantage of having a rotating magnetic field in an alternator is that it allows for the efficient production of alternating current (AC). When a coil is rotated within a magnetic field, an electromotive force (emf) is induced, which generates AC voltage that drives AC current through the coils. This process depends on the rotation rate, the number of coils, their area, and the strength of the magnetic field. The feature of varying sinusoidally in time means that the output voltage can be predictably managed, which is useful in applications requiring consistent and controllable electrical output.
A faster spin rate (greater angular velocity, w) of the generator increases the emf produced, which is reflected in the efficiency of systems like bicycle generators. The ability of alternators to induce a smooth and stable AC supply is critical for many electrical systems, and it highlights the symmetry between the construction of generators and motors. The rotating magnetic field is a key feature of alternators that provides the advantage of versatile and efficient electricity generation.