Alternators and Dynamos

• Describe how alternators function

  A rotating magnet is used with a fixed coil of wire - As the magnet rotates, the magnetic field's direction alternates - This induces an alternating potential difference and an alternating current

  
• Describe how dynamos function

  A rotating coil of wire is used with a fixed magnet. As the coil rotates, It generates a potential difference in one direction

  
• The generator effect is used in alternators to produce an alternating current
• The generator effect is used in dynamos to generate a direct current
• Why is a split ring commutator used in alternators and dynamos?

  So that once the coil has passed the upright position , the connections are reversed. As a result , the direction of the current output is always in the same direction
• In an alternator, the maximum induced potential difference is reached when the rotating coil of wire is horizontal
• In the image below of the alternator, has the maximum induced potential difference been reached?

  Yes - because the rotating coil of wire is horizontal - this means that the rotating coil of wire is cutting through the magnetic field at the fastest rate

  
• In the image below of the alternator, has the maximum induced potential difference been reached?

  No - because the rotating coil of wire is vertical (Or moving parallel to the magnetic field) and so the magnetic field lines are not being cut. This means the induced potential difference is 0

  
• In this image of an alternator, the 2 sides of the coil are now moving in a different direction to what they were in before. What does this mean?

  The potential difference has been reversed

  
• In the image of the alternator below, where do the red and orange lines connect to?

  The red side connects to ring A and the orange side connects to ring B

  
• Why does an alternator produce an alternating potential difference and alternating current?

  Because the two sides of the coil are attached to two different rings
• How can you increase the size of the alternating current in an alternator?

  Increasing the strength of the magnetic field , increasing the number of turns on the coil / the area of the coil , and increasing the rotation speed of the coil
• How can you increase both the size and frequency of the alternating current in an alternator?

  Increase the rotation speed of the coil