Induced Potential, Transformers and the National Grid

• Electrical conductor


  A material that allows electric current to flow through it
• Magnetic field

  The region around a magnet or a current-carrying wire where magnetic forces can be detected
• Potential difference

  The voltage between two points in an electric circuit
• Induced potential difference

  The voltage generated across the ends of a conductor when it moves relative to a magnetic field or when there is a change in the magnetic field it is placed in
• Closed loop


  A complete circuit where the conductor forms a continuous path for the current to flow
• Direction of magnetic field

  The direction of the magnetic field produced by an induced current is such that it opposes the change that induced the current, either the movement of the conductor or a change to the magnetic field
• Generator effect

  The phenomenon where an induced potential difference is used to generate different types of current
• Alternator


  A device that uses the generator effect to produce alternating current

  permanently connected to one of the slip rings

  when a given side of one coils moves upwards through the magnetic field, current will flow through it in one direction
• Dynamo

  A device that uses the generator effect to produce direct current

  split ring commutator, swaps contact every half turn
• Microphone


  A device that takes advantage of the generator effect to convert sound waves into alternating current

  when the sound wave is incident onto the surface of the microphone, the flexible diaphragm vibrates back and forth.

  this causes the coil which is attached to vibrate back and fourth, and so an alternating current is induced in the coil
• Transformer

  and how does it work

  A device that uses electromagnetic induction to transfer electrical energy between two or more circuits through electromagnetic fields

  Alternating current is supplied to the primary coil an alternating magnetic field is produced around it and the iron core

  Therefore, this changing magnetic field causes an alternating p.d to be induced across secondary coil.

  A current will not be induced to the secondary coil if direct current is supplied to primary coil
• Primary coil

  The coil of wire in a transformer connected to the input voltage
• Secondary coil

  The coil of wire in a transformer connected to the output voltage
• Iron core


  A material used in transformers that is easily magnetized
• Alternating current


  An electric current that periodically reverses its direction
• Efficiency

  The ratio of useful energy output to total energy input, expressed as a percentage
• Electrical power


  The rate at which electrical energy is transferred or used
• how can induced potential difference be increased

  1. increasing magnetic field strength

  2. rotating coil more quickly

  3. increasing number of turns in coil

  4. increase area of coil
• what does the alternator allow

  kinetic energy of the coil to be converted into the electrical energy.
• Step up transformers


  More turns on secondary than primary coil, increase the potential difference
• Step down transformers

  decrease the voltage - have more turns on the primary coil