Loudspeakers and Headphones

• What is the motor effect?

  A force experienced by a current-carrying conductor in a magnetic field
• In which devices is the motor effect used?

  Loudspeakers and headphones
• What components are found in a moving coil loudspeaker?

  A cone, coil of wire, and a permanent magnet
• How is the coil of wire connected in a loudspeaker?

  To an alternating current electrical supply
• What happens when current passes through the coil of wire?

  It generates a magnetic field
• How do the magnetic fields interact in a loudspeaker?

  They either attract or repel each other
• What does the resultant force on the cone cause?

  The cone to move in and out
• What happens when the direction of the current switches?

  The direction of the force on the cone reverses
• How is sound produced by the loudspeaker?

  By generating sound waves through cone vibrations
• What does a higher frequency produce in terms of sound?

  A higher pitch sound
• How does changing the frequency of the AC supply affect sound?

  It changes the frequency that the cone vibrates
• What does a lower frequency produce in terms of sound?

  A lower pitch sound
• What happens if the size of the current is increased?

  The amplitude of the vibration increases
• What does an increase in amplitude result in?

  An increase in the volume of the sound
• What are the components of a moving coil loudspeaker?

  • Cone
  • Coil of wire
  • Permanent magnet
• How does the motor effect apply to loudspeakers?

  • Current generates a magnetic field
  • Magnetic fields interact (attract/repel)
  • Cone moves in and out, producing sound
• How does frequency affect sound pitch in loudspeakers?

  • Higher frequency = higher pitch sound
  • Lower frequency = lower pitch sound
• How does current size affect sound volume in loudspeakers?

  • Increased current size = increased amplitude
  • Increased amplitude = increased volume