Understanding how different materials conduct electricity is a cornerstone of physics and engineering. In metals, outer electrons move freely, granting them high conductivity. In contrast, materials like rubber trap electrons, making them insulators. This experiment lets you see these differences in action using everyday items.

Materials Needed

• Size‑D battery
• Battery holder
• Bulb holder (e.g., a small LED or a Christmas light bulb)
• Electrical wire (insulated, gauge 22–24)
• Metal strip (thin sheet or wire)
• Rubber strip or latex glove piece
• Pencil with graphite core

Procedure

1. Insert the battery into the holder and connect the positive lead to one end of the metal strip.
2. Place the bulb in the bulb holder.
3. Use a wire to connect the other end of the metal strip to the bulb’s positive terminal.
4. Connect the bulb’s negative terminal back to the battery’s negative terminal, completing the circuit. The bulb should illuminate, confirming the metal’s conductive properties.
5. Swap the metal strip for the rubber piece. Repeat the connections. The bulb should stay dark, demonstrating rubber’s insulating nature.
6. Replace the rubber with a pencil, ensuring the wire contacts the graphite core. Reconnect the circuit. The bulb should light again, illustrating graphite’s conductivity.

Why It Works

The experiment relies on the movement of electrons. Conductors allow electrons to flow freely, creating a closed circuit that powers the bulb. Insulators prevent electron flow, breaking the circuit. For more technical details, see Electrical conductivity on Wikipedia.

TL;DR

Use a battery, bulb, and various materials to test conductivity: conductors light the bulb; insulators do not.