Motors and Speakers

• Loudspeakers 


  Converts current into sound waves
• A loudspeaker consists of a coil, permanent magnet, cone
• Loudspeaker 1. Current in coil creates electromagnetic field

  2. Field interacts with permanent magnet pushing the cone outwards

  3. Current flow is reversed

  4. Direction of field reverses

  5. Force pulls come back in

  6. A repeated alternating current makes cone go in and out

  7. Cone vibrations cause sound waves
• Electric motors consist of a coil, commutator and a magnetic field
• Fleming's left-hand rule


  Explains why coil turns in a motor
• Dc Motor(Dynamo)

  1.As the coil rotates, it’s direction of movement is perpendicular to the direction of the magnetic field

  2.This induces an A.C current

  3.Split ring commutators reverse the current every half turn

  4.Current is now D.C as it flows in one direction
• What do split ring commutators do ?

  Reverse the current every half turn in a dynamo(D.C motor)