The basic principle of all motors can easily be shown using two electromagnets and a permanent magnet. Current is passed through coil #1 and coil #2 in such a direction that north and south poles are generated next 
to the permanent magnet, as shown in Figure 1. A permanent magnet with a north and south pole is the moving part (the rotor) of this simple motor. In Figure 1 the north pole of the permanent magnet is adjacent to the north pole of the electromagnet. Similarly, the south poles are adjacent to each other. Like magnetic poles repel each other, causing the movable permanent magnet to begin to turn. As it turns in the direction shown, the forces of attraction between the unlike poles becomes strong enough to keep the permanent magnet rotating. The rotating magnet continues to turn until the unlike poles are lined up. At this point the rotor would normally stop (Figure 2).
However, if the current in the electromagnetic coils were suddenly reversed, it would reverse the electromagnetic coil polarity. Now the poles would again be the same and repel each other (Figure 3). The movable permanent magnet rotor would then continue to rotate. If the currents in the electromagnetic coils were reversed every time the magnet turned halfway (180 degrees) the magnet would continue to rotate. This is essentially the way a motor works.
