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Grade 7 Beginner About 10 min Version 1 Awaiting review Premium

Conductor or insulator?

A circuit tester is a cell, a bulb and wires with a gap in them. When a material is placed across the gap, the bulb lights only if electric current can flow through it. Materials that let current flow are conductors: all metals, graphite (pencil lead) and salt water. Materials that do not are insulators: plastic, rubber, glass, dry wood, paper and cloth. Wires are made of copper to carry the current and covered in plastic to keep it from flowing where it should not.

What you will learn

  • Test materials with a simple circuit tester.
  • Classify materials as conductors or insulators.
  • Explain why wires are made of metal and covered with plastic.

Before you start

  • Know that a bulb lights only in a complete circuit.

Materials

  • Copper wire, iron nail, aluminium foil, steel spoon, a coin, pencil lead, salt water, plastic ruler, rubber band, glass rod, dry wooden stick, paper, cotton thread

Equipment

  • 1.5 V cell, small bulb in a holder, connecting wires with crocodile clips

Procedure

  1. Choose a card and place the material across the gap in the circuit.
  2. Watch whether the bulb lights.
  3. Place each card in the conductors or insulators group.