The bene¯ts of AC over DC with regard to generator design is also re°ected in electric motors.
While DC motors require the use of brushes to make electrical contact with moving coils of wire, AC
motors do not. In fact, AC and DC motor designs are very similar to their generator counterparts
(identical for the sake of this tutorial), the AC motor being dependent upon the reversing magnetic
¯eld produced by alternating current through its stationary coils of wire to rotate the rotating
magnet around on its shaft, and the DC motor being dependent on the brush contacts making and
breaking connections to reverse current through the rotating coil every 1/2 rotation (180 degrees).
So we know that AC generators and AC motors tend to be simpler than DC generators and DC
motors. This relative simplicity translates into greater reliability and lower cost of manufacture.
But what else is AC good for? Surely there must be more to it than design details of generators and
motors! Indeed there is. There is an e®ect of electromagnetism known as mutual induction, whereby
two or more coils of wire placed so that the changing magnetic ¯eld created by one induces a voltage
in the other. If we have two mutually inductive coils and we energize one coil with AC, we will
create an AC voltage in the other coil. When used as such, this device is known as a transformer:
The bene¯ts of AC over DC with regard to generator design is also re°ected in electric motors.While DC motors require the use of brushes to make electrical contact with moving coils of wire, ACmotors do not. In fact, AC and DC motor designs are very similar to their generator counterparts(identical for the sake of this tutorial), the AC motor being dependent upon the reversing magnetic¯eld produced by alternating current through its stationary coils of wire to rotate the rotatingmagnet around on its shaft, and the DC motor being dependent on the brush contacts making andbreaking connections to reverse current through the rotating coil every 1/2 rotation (180 degrees).So we know that AC generators and AC motors tend to be simpler than DC generators and DCmotors. This relative simplicity translates into greater reliability and lower cost of manufacture.But what else is AC good for? Surely there must be more to it than design details of generators andmotors! Indeed there is. There is an e®ect of electromagnetism known as mutual induction, wherebytwo or more coils of wire placed so that the changing magnetic ¯eld created by one induces a voltagein the other. If we have two mutually inductive coils and we energize one coil with AC, we willcreate an AC voltage in the other coil. When used as such, this device is known as a transformer:
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