Electricity is one of the most important discoveries humans have made: it powers everything from light bulbs to computers, cars and televisions. Every day, new things are being done with it. One of these is the principle of electromagnetism, which is what makes a toy car motor work. Electromagnetism is the force that transforms electric power from the battery into mechanical power in the toy car's wheels.
There are a number of components that create movement inside the housing of a toy car's electric motor. Two permanent magnets attached at opposite sides sit inside a hollow casing. The armature sits between those magnets. This piece is made up of the commutator--the axle, which sticks through the casing--as well as the rotor coils. The coils, usually made of copper wire, are indirectly attached to the motor's terminals by brushes. The brushes touch, but aren't attached to leads on the rotor coils, allowing them to transfer power, but still rotate.
Everything in the world is made up of tiny particles called atoms. An atom is made up of even smaller particles known as neutrons, protons and electrons. The first two form the nucleus, giving the atom its weight, while the latter floats around the nucleus. When billions of atoms--copper, for example--are stacked and shaped into a straight line, they form copper wire. Attaching electricity to that wire causes the electrons to move. Heading toward the power source's negative terminal, electrons in an atom trade places with those of a neighbor, doing so many times per second to create electric current.
When electricity passes through a wire, such as the copper wires in a toy car's electric motor, the movement causes a small magnetic field. This rotational magnetic field always moves in the same direction. If you look at the wire head-on, the field rotates counter-clockwise.
A magnet is a metal that attracts similar metals. A magnet you place on your refrigerator is a prime example-- a metal magnet clinging to a metal refrigerator. If you place two magnets together, you'll notice they sometimes stick together. Sometimes, they don't. This is caused by the two magnetic "poles"--north and south. Like poles are oppositional. If you push the north pole of one magnet to the other's north pole, they'll pull apart. Conversely, north poles are drawn to south poles.
The rotor coils in a toy car's motor are made of wound copper wire that creates a larger electromagnetic field once electricity is introduced. This is where the brushes come in. If you attach a wire to the coils, it will twist and, possibly, break. The brushes touch long enough to pass electricity through the coil. Once electricity hits the coil, it moves away from the magnets, moving upward. The movement, however, disconnects the brush, so the coil falls, just long enough for the brush to hit the opposite side, restarting the process. This happens twice every time the armature makes a full rotation.