uses of magnetism

• What happens when a current-carrying wire is placed in a magnetic field?

  The wire experiences a force.
• What is the motor effect?

  A wire carrying current creates a magnetic field.
• What is the equation for force in the motor effect?

  F = BIL
• What does magnetic flux density measure?

  It measures the strength of the magnetic field.
• How can you increase the force on a wire in a magnetic field?

  Increase the magnetic flux density.
• What are the factors that can increase the force on a wire in a magnetic field?

  • Increase the magnetic flux density
  • Increase the length of the wire
  • Increase the current
• What does Fleming’s Left Hand Rule help determine?

  The direction of force, field, and current.
• What do the fingers represent in Fleming’s Left Hand Rule?

  Thumb: motion, First finger: field, Second finger: current.
• What happens if the conductor is parallel to the magnetic field?

  It will not experience a force.
• What is the generator effect?

  Relative motion induces a potential difference.
• What happens to the current when the direction of movement switches in the generator effect?

  The direction of current switches as well.
• What is required for the generator effect to occur?

  The wire must pass through the magnetic field.
• What factors affect the size of the induced potential difference or current?

  • Strength of the magnetic field
  • Speed of the movement of wire
  • Number of turns or shaping the wire into a coil
• How does switching the poles of the magnet affect the induced current?

  It switches the direction of the induced current.
• What happens when the induced current opposes the movement of the magnet?

  It makes it harder for the magnet to move.
• How does the induced current relate to the movement of the magnet?

  • Induced current has its own magnetic field.
  • It opposes the movement of the magnet.
  • Energy transfers from magnet movement to current movement.
• What is the role of the coil in a loudspeaker?

  It generates a magnetic field when current passes.
• How does the interaction between the coil's magnetic field and the permanent magnet's field affect the cone?

  It causes the cone to move, generating sound waves.
• What happens when the current direction in the coil switches?

  The direction of the force on the cone reverses.
• How does frequency affect the sound produced by a loudspeaker?

  A higher frequency produces a higher pitch sound.
• What happens when sound waves hit the diaphragm of a microphone?

  They cause the diaphragm to vibrate.
• What occurs when the coil of wire in a microphone moves in the magnetic field?

  It induces a potential difference across the wire.
• How does the potential difference behave as the coil moves in the magnetic field?

  The potential difference switches direction.
• What type of electrical supply is connected to the coil in a loudspeaker?

  a.c. electrical supply
• What is located inside the coil of wire in a loudspeaker?

  A permanent magnet
• What happens when current passes through the coil in a loudspeaker?

  It generates a magnetic field
• How do the magnetic fields of the coil and permanent magnet interact?

  They attract or repel each other
• What causes the cone in a loudspeaker to move?

  The resultant force from magnetic interaction
• What happens to the cone when the current switches direction?

  The direction of the force reverses
• What does a higher frequency produce in sound?

  A higher pitch sound
• How can the volume of sound be changed in a loudspeaker?

  By changing the amplitude of vibrations
• What happens when sound waves hit the diaphragm of a microphone?

  It causes the diaphragm to vibrate
• What does the coil of wire do in a microphone when it vibrates?

  Moves in and out of the magnetic field
• What effect does the coil moving in the magnetic field have in a microphone?

  It induces a potential difference
• What happens to the potential difference as the coil moves backwards and forwards?

  It switches direction
• When is the maximum potential difference induced in a microphone's coil?

  When the coil is horizontal
• Why does the potential difference fall to 0 when the coil is vertical?

  Because it moves parallel to the magnetic field
• What happens to the potential difference as the coil continues to move?

  A potential difference is induced with reversed direction
• What is an alternator?

  A coil rotating in a magnetic field
• What do commutators do in an alternator?

  Allow current to pass out of the coil