How Are AC and DC Motors Alike

http://cr4.globalspec.com/thread/1329

because it follows then that when a motor is powered from a supply and is runing at full speed it will be generating a voltage. As determined from lenz's law. This induced E.M.F is opposite in direction to the supply voltage it is known as back E.M.F. This generated voltage is always less then the supply voltage due to the voltage drop in the armuture windings. This works in both AC and DC

They both spin because of the electro repulsive effect. DC direct current uses coils and permanent magnets. AC alternating current uses a voltage that goes positive and then passes through a zero voltage to change polarity to a negative voltage (sign wave) you can also get a square wave where the wave shape is like that of a squared off shape vertical to Begin flat across the top and back down to cross over and go horizontal before going back up again; this repeats for as long as you like.

AC is used because it can be transformed up or down in voltage you can only convert down with DC unless you use a chopper supply.

The output shafts of both rotate and can be coupled to devices to transfer energy from the electrical supply to the load.

That's about it.