7.2.2 Electric Motors

• An electric motor utilizes the motor effect to convert electrical energy into mechanical energy.
• The rotating part of an electric motor is called the rotor.
• What is the purpose of the commutator in an electric motor?

  Reverse the current
• The commutator in an electric motor reverses the current in the rotor coils to maintain consistent rotation
• A stronger magnetic field in an electric motor increases the force, thereby enhancing the motor effect
• The rotor in an electric motor produces mechanical energy by spinning within a magnetic field
• Steps in the process of electrical energy conversion to mechanical energy in an electric motor

  1️⃣ Electric current is passed through the rotor

  2️⃣ The rotor is placed within a magnetic field

  3️⃣ Interaction between rotor and magnetic field creates a force

  4️⃣ Rotor spins to generate mechanical energy

  5️⃣ The commutator reverses the current to maintain rotation
• Match the side of the coil with its force direction in an electric motor:

  Left side ↔️ Upward force

  Right side ↔️ Downward force
• Electric motors are used in industrial machinery to power conveyor belts and pumps.


  True
• What is an electric motor used to convert?

  Electrical to mechanical energy
• What is the motor effect caused by?

  Current-carrying conductor in a magnetic field
• The stator in an electric motor creates the magnetic field.


  True
• Steps of electrical energy conversion to mechanical energy in an electric motor

  1️⃣ Electric current passes through the rotor coil

  2️⃣ The rotor is placed within a magnetic field created by the stator

  3️⃣ Interaction between the magnetic field and rotor current creates a force

  4️⃣ The commutator reverses the current in the rotor coils

  5️⃣ The rotor spins, producing mechanical energy
• What is the role of the rotor in an electric motor?

  Produces mechanical energy
• What happens to the force on a conductor when the magnetic field strength is weak?

  Force becomes small
• What is the motor effect in an electric motor?

  Force on current in field
• What is the role of the commutator in an electric motor?

  Reverses current
• The motor effect causes forces on a coil in a magnetic field that create torque and rotation.


  True
• Household appliances such as refrigerators and washing machines use electric motors to provide efficient operation
• An electric motor converts electrical energy into mechanical energy.


  True
• The interaction between the magnetic field of the stator and the current-carrying rotor coils produces a force.
• What determines the strength of the force on a current-carrying conductor in a magnetic field?

  Magnetic field strength
• The magnetic field exerts a force on a current-carrying conductor placed within it.


  True
• An electric motor converts electrical energy into mechanical energy using the motor effect.


  True
• The force on a current-carrying conductor in a magnetic field depends on the magnetic field strength
• What is the combination of upward and downward forces on the coil called in an electric motor?

  Torque
• Why are electric motors used in industrial machinery?

  Enhanced productivity