Generator effect

• A potential difference is generated when a wire experience changes in magnetic field
• Moving either the wire or the magnet would generate a potential difference in a wire
• A wire moving up and down repeatedly perpendicular to a magnetic field will: generate an alternating potential difference
• Potential difference (or voltage) is needed for an electric current to flow.
• A potential difference can be induced across an electrical conductor by:

  • Moving a conductor (a wire or a coil) at right-angles to a magnetic field.
  • moving a magnet into a coil of wire
  • -this is called the generator effect
• The induced current in the conductor creates its own magnetic field
• The induced magnetic field will oppose the change that created it.

  For example, if a magnet is moved into a coil of wire, the new magnetic field repels the magnet back out of the coil
• The size of the induced potential difference (p.d.) can be increased in three ways:

  • By 

  increasing the speed of movement between the conductor and magnetic field.

  • By using a

   stronger magnetic field.

  • By adding 

  more turns to the wire coil.
• If you move the conductor or magnet in theopposite direction, the direction of the p.d. (and current) is also reversed.
• Alternators use the generator effect to make an alternating current.