Electric Motor Functionality Lecture Notes

Overview

• Focus: Understanding how an electric motor works, specifically for higher-tier students.
• Previous Knowledge: The motor effect - when a conductor carrying current within a magnetic field experiences a force.
• Key Concept: Use Fleming's left-hand rule to determine the direction of force.

Motor Effect

• Motor Effect: A force experienced by a current-carrying conductor in a magnetic field.
• Fleming’s Left Hand Rule: Used to determine the direction of the force on the conductor.

Electric Motor

Basic Principle

• A loop of wire carrying current is placed in a magnetic field.
• Current directions:
  • Left side: Current runs back to front.
  • Right side: Current runs front to back.
• Forces:
  • Left side: Force acts upwards.
  • Right side: Force acts downwards.
• This creates moments (torque) causing the loop to rotate clockwise.

Rotational Challenges

• Problem: At 90 degrees, the loop stops rotating.
• Post-90-degree rotation:
  • Left side: Force acts downwards.
  • Right side: Force acts upwards.
• Forces push loop back to the 90 degrees position.

Solution: Split Ring Commutator

• Function: Switches the direction of the current as the loop rotates beyond 90 degrees.
• Components:
  • Split Ring Commutator: A split metal ring.
  • Conducting Brushes: Allow current to pass to the ring.

Continuous Rotation

• Direction Reversal: At each half-turn, the current's direction is reversed.
• Result: Forces remain consistent (left force upwards, right force downwards).
• Outcome: Continuous clockwise motion of the motor.

Additional Resources

• Practice questions available in the revision workbook.
• Workbook and additional materials accessible via provided link.