Electric Motors (HT only)

• What is the primary function of an electric motor?

  To rotate using a magnetic field
• How does a coil of wire in a magnetic field behave?

  It tends to rotate when carrying current
• What is the basis of an electric motor?

  A coil of wire carrying current in a magnetic field
• How can a simple electric motor be built?

  Using a coil of wire free to rotate
• What happens when an electric current flows through a coil in a magnetic field?

  The current moves in opposite directions on each side
• What causes the coil to rotate in an electric motor?

  Forces acting in opposite directions on the coil
• What must happen to the direction of the current for the coil to keep rotating?

  The direction must be reversed every half turn
• What is achieved by reversing the current direction in a coil?

  It allows continuous rotation of the coil
• What is a split-ring commutator used for in an electric motor?

  To reverse the current direction in the coil
• What is the effect of increasing the number of turns in a coil?

  It increases the effect of the magnetic field
• What are the components of a split-ring commutator in an electric motor?

  • Coil of wire
  • Split-ring mechanism
  • Brushes for contact
• What direction does the coil rotate in a split-ring commutator?

  Clockwise
• What is the role of brushes in an electric motor?

  To maintain contact with the split-ring commutator
• What material is commonly used for brushes in electric motors?

  Graphite
• How does the contact between brushes and the commutator affect motor performance?

  It ensures consistent current flow to the coil
• What happens if the brushes wear out in an electric motor?

  The motor may stop functioning properly
• What is the purpose of the metal or graphite brush in an electric motor?

  To conduct electricity to the coil
• What is the relationship between the number of turns in a coil and the strength of the magnetic field?

  More turns increase the magnetic field strength
• How can the efficiency of an electric motor be improved?

  By increasing the number of turns in the coil
• What are the key components of an electric motor's operation?

  • Coil of wire in a magnetic field
  • Current flowing through the coil
  • Forces acting on the coil
  • Split-ring commutator for current reversal
  • Brushes for electrical contact