Edexcel iGCSE Physics -2.22P Conductors and Insulators- Study Notes- New Syllabus

Electrical Conductors and Insulators

Materials can be classified as electrical conductors or electrical insulators based on how easily they allow electric current to flow.

This classification is essential for the safe and effective design of electrical circuits and appliances.

Electrical Conductors   

An electrical conductor is a material that allows electric current to flow easily.

• Conductors have many free electrons.
• These electrons can move through the material.
• Conductors have low resistance.

Common Electrical Conductors

• Metals such as copper, aluminium, iron, and steel.
• Graphite (a form of carbon).
• Salt solutions (electrolytes).

Metals are the most common conductors used in electrical wiring.

Electrical Insulators

An electrical insulator is a material that does not allow electric current to flow easily.

• Insulators have very few free charge carriers.
• Charge cannot move freely.
• Insulators have high resistance.

Common Electrical Insulators

• Plastics (PVC, rubber).
• Glass.
• Dry wood.
• Ceramics.

Plastics are widely used to protect users from electric shock.

Why Metals Conduct and Plastics Insulate

• Metals contain free electrons that can move.
• Plastics have tightly bound electrons.
• This difference determines conductivity.

Link to Current Formula

Electric current depends on resistance:

\( \mathrm{I = \dfrac{V}{R}} \)

• Conductors → low \( \mathrm{R} \) → higher current.
• Insulators → high \( \mathrm{R} \) → very small or zero current.

Uses in Everyday Life

• Copper wires carry current in circuits.
• Plastic insulation prevents electric shock.
• Metal plugs conduct electricity safely.

Key Idea

• Conductors allow current to flow.
• Insulators resist current flow.
• Both are essential for safe electrical systems.

Important Points to Remember

• Most metals are conductors.
• Most plastics are insulators.
• Materials are chosen for safety and efficiency.