Английский язык: Аннотирование и реферирование текста

256 By understanding how a motor works you can learn a lot about magnets, electromagnets and electricity in general. In this article, you will learn what makes electric motors tick. Inside an Electric Motor Let's start by looking at the overall plan of a simple two-pole DC electric motor. A simple motor has six parts: Armature or rotor, Com- mutator, Brushes, Axle, Field magnet, DC power supply of some sort. An electric motor is all about magnets and magnetism: A motor uses magnets to create motion. If you have ever played with magnets you know about the fundamental law of all magnets: Opposites attract and likes repel. So if you have two bar magnets with their ends marked "north" and "south," then the north end of one magnet will attract the south end of the other. On the other hand, the north end of one magnet will repel the north end of the other (and similarly, south will repel south). Inside an electric motor, these attracting and repelling forces create rotational motion. In the above diagram, you can see two magnets in the motor: The armature (or rotor) is an electromagnet, while the field magnet is a permanent magnet (the field magnet could be an electromagnet as well, but in most small motors it isn't in order to save power). Toy Motor The motor being considered here is a simple electric motor that you would typically find in a toy: This is a small motor, about as big around as a dime. From the outside you can see the steel can that forms the body of the motor, an axle, a nylon end cap and two battery leads. If you hook the battery leads of the motor up to a flashlight battery, the axle will spin. If you reverse the leads, it will spin in the opposite direction. The nylon end cap is held in place by two tabs that are part of the steel can. By bending the tabs back, you can free the end cap and re- move it. Inside the end cap are the motor's brushes. These brushes transfer power from the battery to the commutator as the motor spins: