Th­e basic idea behind an electromagnet is extremely simple: By running electric current through a wire, you can create a magnetic field.

By using this simple principle, you can create all sorts of things, including motors, solenoids, read/write heads for hard disks and tape drives, speakers, and so on. In this article, you will learn exactly how electromagnets work..

Basic electromagnet

A Regular Magnet

Before talking about electromagnets, let’s talk about normal “permanent” magnets like the ones you have on your refrigerator and that you probably played with as a kid.

An electromagnet is the same way, except it is “temporary” — the magnetic field only exists when electric current is flowing….

An Electromagnet

An electromagnet starts with a battery (or some other source of power) and a wire. What a battery produces is electrons.

If you look at a battery, say at a normal D-cell from a flashlight, you can see that there are two ends, one marked plus (+) and the other marked minus (-). Electrons collect at the negative end of the battery, and, if you let them, they will gladly flow to the positive end. The way you “let them” flow is with a wire. If you attach a wire directly between the positive and negative terminals of a D-cell, three things will happen:

  1. Electrons will flow from the negative side of the battery to the positive side as fast as they can.
  2. The battery will drain fairly quickly (in a matter of several minutes). For that reason, it is generally not a good idea to connect the two terminals of a battery to one another directly. Normally, you connect some kind of load in the middle of the wire so the electrons can do useful work. The load might be a motor, a light bulb, a radio or whatever.
  3. A small magnetic field is generated in the wire. It is this small magnetic field that is the basis of an electromagnet.

Applications of electromagnets in real life….

Electric Motors

  • Electric motors produce motion from electromagnetism. Although electric motors take many forms, they all work on the same basic principle: electromagnetism exerts force on metal. This means that metal can be made to move if it is placed between electromagnets. Controlling the electrical flow to the electromagnets allows the motion of the metal to be controlled, producing mechanical motion. Complex motors involving numerous moving parts and electromagnets can be found in most electrical devices, from electric fans to electric cars.

Magnetic Recording

  • Electromagnets are essential to the process of recording using magnetic tapes, as with audio cassettes and videotapes. This method uses magnetism-sensitive strips of tape, which are passed through an electromagnetic field. Pulses of magnetism from the electromagnet imprint onto the tape, recording sound. This sound can then be played back when the tape is passed by another electromagnet wrapped in coiled wire. This generates an electrical charge which the tape player’s speakers can interpret into sound….

Speakers

  • All speakers contain electromagnets. Speakers comprise an electric cone attached to an electromagnet. The electromagnet is positioned in front of a stationary magnet. As electricity is passed through the electromagnet, its electrical polarity is reversed. Running pulses of electricity through the electromagnet rapidly causes it to be attracted to and repulsed from the magnet, causing the cone to vibrate. The shape of the cone amplifies the vibrations, causing it to emit sound….

Doorbells

·  Doorbells use electromagnets to produce chimes. When the doorbell button is pressed, a pulse of electricity is sent to the doorbell speaker. The speaker contains an electromagnet connected to a spring-loaded moving part called a solenoid. The electromagnet causes the solenoid to move forward, striking a bell. When the button is released, the solenoid is forced back by the spring, and hits another bell, completing the melody. More complex doorbell melodies exist, and use a series of electromagnets and solenoids that activate in succession when the button is pressed….

Watch this video….

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