Magnetic Aquarium

A red and blue exhibit table with a yellow, white and purple information panel on top, sits in front of two green and blue walls. On the table sits a blue, black and clear perspex cylinder shpaed aquarium.
A red and blue exhibit table with a yellow, white and purple information panel on top, sits in front of two green and blue walls. On the table sits a blue, black and clear perspex cylinder shpaed aquarium.

Magnetic fields can be seen when magnetic metals align against a magnet's poles.

How it works

Slide a magnet across magnetite in a Perspex box and observe three dimensional magnetic fields.

Things to try or ask around the exhibit

  • What do you notice when you move the magnet beneath the ‘aquarium’?
  • How do the magnetite particles line up when you move the magnet nearby?
  • If the ‘aquarium’ contained other types of metals, would they all react the same way to the magnet?

Background

The powdery black material is called magnetite (crushed iron oxide). Not all metals respond to magnets. Iron and steel can be magnetised. Aluminium however, cannot be magnetised, so if aluminium oxide was placed in the aquarium instead of iron oxide, it would not respond to the magnet.

When a metal is magnetised, tiny ‘domains’ inside the metal line up to match the magnet’s north and south poles. Usually, the domains return to a random order when the magnet is taken away.

Finding the science in your world

Recycling plants use magnets to separate steel cans from aluminium cans. An industrial magnet picks up steel cans (which are magnetic), while aluminium cans are left behind to be collected separately.