4.2.5 motor examples

• DC Motors

  • A coil carrying an electrical current will rotate in a magnetic field. This is because the current going up one side of the coil is flowing in the opposite direction to the current coming back down the other side.
  • Using Fleming’s left hand rule we can see that one side of the coil will move downwards and the other side of the coil will move upwards.
• To increase the force acting on the coil of a DC motor:

  • stronger magnetic field
  • more turns on the coil
  • higher current through the coil
• Loudspeakers

  A moving-coil loudspeaker or set of headphones has an electromagnet inside a coil. A signal is passed to the loudspeaker in the form of a changing current.
• Loudspeakers

  • change in current causes change in magnetic field. as the direction of current changes, direction of magnetic field in induced electromagnet changes
  • a stationary magnet repeatedly attracts and repels the electromagnet
  • speakers vibrate, move backwards and forwards
  • this creates sound waves
• A moving-coil loudspeaker or set of headphones has an electromagnet inside a coil.
• A coil carrying an electrical current will rotate in a magnetic field, provided the current going up one side of the coil is flowing in the opposite direction to the current coming back down the other side.