The Alternator and Dynamo

• What happens when a conducting wire passes through a magnetic field?

  A potential difference is induced in the wire
• What is the generator effect?

  Inducing current when a wire moves in a field
• How does an alternator generate alternating current?

  • Coil of wire rotates in a magnetic field
  • Connected to two metal rings called commutator
  • Potential difference induced as wire moves
  • Produces alternating potential difference and current
• What is the maximum potential difference in an alternator?

  When the coil is horizontal
• Why does the potential difference fall to zero when the coil is vertical?

  Because the coil moves parallel to the field
• How does the direction of potential difference change in an alternator?

  It reverses as the coil rotates
• What is the definition of alternating current (AC)?

  Current that reverses direction periodically
• How can you increase the size of the alternating current in an alternator?

  By increasing magnetic field strength
• What happens to the alternating current if the coil's area is increased?

  The size of the alternating current increases
• What is a key feature of a dynamo?

  It has a split ring commutator
• How does a dynamo produce direct current (DC)?

  The direction of potential difference does not reverse
• How many peaks are there in the potential difference graph for a dynamo during one full rotation?

  Two peaks
• Why does the potential difference become zero when the coil is vertical in a dynamo?

  Because it moves parallel to the magnetic field
• What are the differences between an alternator and a dynamo?

  • Alternator: Produces alternating current (AC)
  • Dynamo: Produces direct current (DC)
  • Alternator uses a commutator
  • Dynamo uses a split ring commutator
• What is the effect of increasing the rotation speed of the coil in an alternator?

  It increases both size and frequency of AC
• What is the role of the commutator in an alternator?

  To allow current to pass out of the coil
• What happens to the potential difference as the coil continues to rotate in an alternator?

  It changes direction and varies in size
• How does the potential difference graph for an alternator differ from that of a dynamo?

  Alternator graph shows alternating peaks; dynamo shows two peaks