Electricity: Conductors and Insulators

Electricity

Conductors and Insulators
Learning Objectives
  • Understand the difference between electrical conductors and insulators.
  • Learn about uses for conductors and insulators.
  • Test some materials for electrical conduction or insulation.
Definitions
  • Conductors: Materials that conduct electricity and allow electric current to flow.
  • Insulators: Materials that do not allow electric current to flow through them.
Conductors
  • Characteristics:
    • Allow current to flow through them.
    • In conductors, particles called electrons are free to move.
  • Examples: All metals, commonly used materials include:
    • Copper (for most household wiring)
    • Aluminium and steel (used for long-distance wiring due to cost).
  • Applications:
    • Wires carrying electric current are primarily made from metal.
    • Printed circuit boards substitute wires with copper tracks (coated for safety).
Movement of Electrons in Conductors

  • When the circuit is OFF:

    • Free electrons move randomly (no specific direction, resembling kids running around a playground).

  • When the circuit is ON:

    • Voltage from a battery creates a push, causing free electrons to drift from the negative terminal to the positive terminal (analogous to train wagons moving forward when a train starts).

  • The process of electrons moving in the circuit constitutes electric current.

Insulators
  • Characteristics:
    • Do not allow current to flow; most non-metals are insulators (e.g., plastic, wood, air).
    • Electrons in insulators are tightly bound to their atoms and cannot move freely.
  • Safety Purpose:
    • Insulators protect people from electric shock (e.g., plastic coatings on plugs and wires).
  • Applications:
    • Insulation is used to color-code wires for identification and safety.
Understanding Electron Movement in Insulators
  • Analogy:
    • Think of students glued to their chairs (like electrons in insulators); they cannot move regardless of external signals (no current can flow).
Conductors vs Insulators Summary

  • Conductors:

    • Electrons are FREE to move.
    • Allow current flow.

  • Insulators:

    • Electrons are NOT FREE to move.
    • Prevent current flow.
Important Comparisons
  • During circuit operation:
    • Electrons in conductors move towards the positive terminal, while in insulators, electrons do not move at all.
Practical Assessment Activities
  • Classify various materials as conductors or insulators and provide reasons.
  • Discuss why copper is preferred for wiring instead of silver despite the latter being a better conductor.
  • Explain the role of insulation in preventing electrical hazards.
Glossary
  1. Conduct Electricity: To allow current to flow.
  2. Allow Current to Flow: Having electrons that are free to move.
  3. Conductor: A material where electrons can move freely, facilitating current flow.
  4. Insulator: A material where electrons are not free to move, preventing current flow.
  5. Inhibit: To stop something from happening.