induction

• What happens when an electrical conductor moves relative to a magnetic field?

  A voltage(potential difference) is induced across the conductor
• What happens to an electrical conductor when there is a change to the magnetic field that it is placed in

  The voltage is also changed
• How can you produce an electric current using a magnet and a conductor on a small scale?

  • Move a coil of wire between magnetic poles
  • Move a magnet within a coil of wire
  • once a voltage is unduced , if there is a complete circuit , a current will also be induced
• How is electrical current produced on a large scale?

  An electromagnet is rotated around a coil
• What factors affect the size of an induced voltage?

  • Number of turns on the coil of wire
  • Strength of the magnetic field
  • Speed of the movement
• What is required for an induced potential difference to cause a current flow?

  The conductor must form a closed loop
• How is the generator effect used to generate different types of current?

  • In an alternator to produce alternating current
  • In a dynamo to produce direct current
• How does a dynamo generate current?

  A coil rotates inside a magnetic field , a commutator is used to ensure it continues rotating in the same direction , therefore keeping the current flowing in the same direction(d.c)
• How is electromagnetic induction used in alternators to generate alternating current?

  A coil rotates in a magnetic field , the end of the coil is attached to slip rings which will cause the current to change direction while rotating
• What electromagnetic effect does a microphone take advantage of and how?

  • The generator effect
  • Converts pressure variations in sound waves into alternating current
• How do loudspeakers make use of the motor effect?

  They convert variations in the current of an electrical circuit into the pressure variations which produce audible sound
• Explain how a loudspeaker works.

  • A cone wrapped in wire is connected to an a.c. power supply
  • Placed in a permanent magnetic field
  • when current flows through the wire it creates a magnetic field interacting with the permanent field
  • Produces a force causing the cone to vibrate, producing sound
• How is the pitch of the sound from a loudspeaker changed?

  • The frequency of the a.c. current is altered
  • Creates a different frequency of vibration in the cone
• How do microphones convert sound into electrical signals?

  • Sound produces pressure variations causing diaphragm vibration
  • A coil connected to the diaphragm moves with it
  • Movement in a magnetic field(wire) induces a potential difference
  • A complete circuit creates a current , therefore it is converted into electrical signals