• Electromagnets are vital to a speaker's function.speaker image by CraterValley Photo from Fotolia.com
  
  Electromagnets are used in many everyday devices and machines. Electromagnetism occurs when electricity is run through a metal coil, which causes it to become magnetic. When the current stops, the coil ceases to be magnetic. This simple ability to turn magnetism on and off instantly has led to electromagnets becoming crucial devices in many modern electronics.
  
  

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.