Pop Fuse

What do you get when you cross a battery, a balloon and some steel wool? An explosion of rubber, of course!

Australian Curriculum links

  • Science > Physical Sciences > Year 6 > ACSSU097

You'll need

  • balloon
  • steel wool
  • sticky tape
  • 2 wire leads with alligator clips
  • 9 V battery

Try this

  1. Inflate the balloon as much as possible (without popping it) and tie it off.
  2. Pull out a single thread of wire from the steel wool.
  3. Tape the thread of wire to the side of the balloon. The wire should lie flat against the balloon, with 3 centimetres of wire exposed at each end.
  4. Attach an alligator clip to each end of the thread of wire.
  5. Connect the loose ends of the wire leads to opposite battery terminals.
  6. Wait a few seconds (or until the balloon pops).

What's happening?

When the wire is attached to the battery, electricity begins to flow. This makes the wire heat up. Once it is hot enough, it burns a small hole in the rubber, causing the balloon to pop.
Electricity is the movement of charges called 'electrons'. When lots of electrons are moving to make the electricity flow, we say it has a high current. When only a few electrons are moving to make the electricity flow, we say it has a low current.

As electricity moves through a wire, heat is produced as a result of electrical resistance in the wire. The amount of heat produced is directly related to the size of the electrical current. Therefore as the current increases, more heat is produced and the steel wool becomes hotter.

The steel wool wire acts in the same way as a fuse. Fuses were once a common household safety device. A fuse is designed to heat up and break if the current in an electrical circuit is too high. In households, a high current can often indicate a faulty appliance, which can be very dangerous. In the event of a high current, the fuse wire heats up and breaks. This instantly cuts the power and minimises the risk of electrocution and injury. Once the faulty appliance is removed, the broken fuse can be replaced. Modern circuit breakers are now used instead of fuses. They work with the use of special electromagnets called 'solenoids' which do not need replacing after use.

Further information

Sandi Weld from Michigan won the 72nd World Champion Liar Contest when she claimed her sheep began growing steel wool after she moved to a place called Iron Mountain. She reported that when she sheared her sheep in spring, she ended up with four kilograms of steel wool. She attributed this to the mineral-rich grass the sheep had been grazing on all season. What a whopper of a lie and an appropriately rewarded one!