Lecture Notes: Understanding Electric Motors

Introduction

• Electric motors are present in various household devices (e.g., toys, fans, hairdryers).
• A motor starts rotating when turned on due to the interaction between electricity and magnets.

Basics of Electricity and Circuits

• Circuit Components: Battery, wires, and a device (e.g., a light bulb).
• Flow of Electricity:
  • Electricity flows in a complete circuit.
  • Current flow can be reversed by flipping the battery.
  • Some devices behave differently based on current direction.

Basics of Magnets

• Magnet Characteristics:
  • North and south poles attracting and repelling.
  • Permanent magnets are always "on," made of aligned magnetic domains.
• Magnet Interactions:
  • Opposite poles attract; same poles repel.
  • Magnets can be of various shapes and sizes.

Electromagnets

• Creation:
  • Created by wrapping a wire around a metal bolt and running a current through it.
  • Acts like a permanent magnet with north and south poles.
• Properties:
  • Can be turned on and off by controlling the current.
  • Polarity can be reversed by flipping the battery or switching wires.

Concept of Spinning Electromagnet

• Replacing permanent magnets with electromagnets can induce rotation.
• Electromagnet and Current:
  • Current flow impacts magnetic polarity.
  • Reversing polarity can keep the electromagnet spinning.

Improving the Motor

• Permanent Magnets: Stronger, curved side magnets replace initial magnets.
• Armature: Metal loop replaces the bolt and wires, forming a complete circuit.
• Commutator:
  • A ring with gaps that switches contacts, maintaining continuous current flow.
  • Brushes maintain contact, allowing polarity reversal for continuous spinning.
• Motor Enhancements:
  • Multiple loops on armature for consistent speed.
  • Stronger electromagnets from more wires tightly wrapped.
  • More electricity increases torque, leading to faster spinning.

Key Motor Components

• Stator: The non-moving part (usually the permanent magnets).
• Rotor: The spinning armature in the middle.
• Axle: Central rod that protrudes from the motor.
• Torque: The spinning force of the motor.

Applications of Electric Motors

• Found in devices powered by batteries (toys, fans, electric knives).
• Convert spinning motion to other types of movement (e.g., fan blades, knife blades).

Additional Learning Resources

• Brilliant: An app for learning math and science, offering interactive problem-solving.
• Course availability on electricity and magnetism for deeper understanding.

Note: This summarized content gives an overview of the working and components of electric motors, and how they are fundamental to various electronic devices.