DC motors

Electric current from a battery or other source that is moving in one direction only is called direct current. If the battery is connected to the coil of a simple motor, the coil is magnetized, with its opposite ends there are two poles - negative and positive. Because opposite poles are attracted together, North and South poles of the coil are sent respectively to South and North poles of the permanent magnet. These attractive forces cause the coil to rotate on its axis, and soon its terminals are placed at opposite poles of the permanent magnet.
However, at this point, an automatic switching device (collector) directs current in the opposite direction. Collector simple DC motor consists of a copper ring that is cut in half and attached (with gasket dielectric) on the axis of the rotor. The ends of the coil are connected to two halves of the ring. The current passes through the coil and gets on a couple of coal contact brushes that touch opposite sides of the manifold. During rotation of the rotor, each brush alternately communicates with both sides of the coil.