Fuse with Steel Wool

This demonstration shows how a fuse works using strands of steel wool in a simple circuit. When the circuit is shorted, the current heats the steel wool until it glows and melts, breaking the circuit.

1. Set up a simple circuit with a power source, a light bulb, and a holder for a small piece of steel wool to act as a fuse.
2. Insert a few thin strands of steel wool into the circuit in place of the fuse.
3. Turn on the circuit with the light bulb connected; the bulb lights normally.
4. Create a short circuit (for example, bypass the bulb).
5. Observe as the increased current causes the steel wool strands to glow red-hot and melt, breaking the circuit.

Gr8 Electrical Fuse Wire of steel wool - Peter “mac” McEwan:

📄 How fuses work - IOP: https://spark.iop.org/how-fuses-work

• Try different thicknesses of steel wool to see how much current they can handle before melting.
• Replace the bulb with a small motor or other load to compare how the fuse responds.
• Compare steel wool with a thin copper wire to highlight why certain materials are chosen for fuses.
• Use commercially available low-current fuse wire.

• Use low-voltage DC power (e.g., batteries) to reduce risk.
• Perform the demo in a fireproof tray or on a non-flammable surface.
• Do not use mains electricity for this demonstration.
• Do not touch the steel wool immediately after it burns—it will be hot.

• Why does the steel wool melt when the circuit is shorted? (Excess current produces heat through resistance.)
• How does this relate to the purpose of a fuse in a household circuit? (A fuse is designed to melt and break the circuit before the wiring overheats.)
• Why is steel wool suitable for this demonstration? (It has higher resistance than copper, is thin, and heats up quickly.)
• What would happen if you used a thicker piece of steel wool? (It would take longer to heat and may not act as an effective fuse.)