AC Generator

• Each side of the coil travels upwards then downwards then upwards etc. so the current flows backwards then forwards then backwards etc. so it is an alternating current.

  
• When the coil is rotated, it cuts magnetic field lines, so an EMF is generated, which makes a current flow.

  
• The brushes are 2 contacts which rub against the slip rings and keep the coil connected to the outside part of the circuit, usually made of carbon.

  
• The coil is made of insulated copper wire and is rotated by turning the shaft; the slip rings are fixed to the coil and rotate with it.

  
• The current is maximum when the coil is horizontal since field lines are being cut at the fastest rate and 0 when the coil is vertical, since it is cutting NO field lines.

  
• The EMF can be increased by:

  • increasing the number of turns on the coil
  • increasing the area of the coil
  • using a stronger magnet
  • rotating the coil faster