How it works

Turn the top handle. Turn the bottom handle. How do the interesting shapes form?

The glass tray contains a thin layer of a special material called ferrofluid, a liquid that becomes strongly magnetized when it is near a magnetic field. Turning the handles moves strong magnets closer or farther from the ferrofluid, changing the magnetic field.

When the two magnets approach the ferrofluid, they change the shape and strength of the magnetic field between them. The shapes that form in the ferrofluid represent the magnetic forces acting on the ferrofluid.

What's going on?

Have you ever heard of a liquid called ferrofluid? The term ferrofluid is of Latin origin. In Latin, ferro means magnet. But with the English term fluid attached to it; this changes its whole meaning. Fluid according to the dictionary is liquid. Ferrofluid is a liquid that has very small pieces of a magnetic substance.

This fluid can transform into a powerful magnet. How is this possible? When we think of magnets, we usually think of solid metal objects. Ferrofluid is filled with very small iron particles. Solid magnets are also made of iron particles. Just because ferrofluid is a liquid doesn't mean it is a less powerful magnet. When you turn the top and bottom handles, you are watching the ferrofluid's power in the presence of a magnetic field. The pieces of metal in the ferrofluid are so small that the ferrofluid can stay in a liquid state as it is exposed to the magnet field – allowing it to make interesting shapes.

Try this at home!

You thought you'd get to do an experiment at home with ferrofluids? Nope. Sorry, too messy, and ferrofluids can be hazardous. But how about learning a magic trick that uses a magnet?

What you'll need:

• string
• magnet
• scissors
• paper clip
• scotch tape
• glue (optional)
• clean glass gar with a metal lid

What you'll do:

1. Cut the string about the length of the jar from top to bottom.
2. Tie the paper clip to one end of the string.
3. Tape the other end of the string to the bottom (inside) of the jar.
4. Tape or glue the magnet to the inside of the lid.
5. Now show your audience the jar with the paper clip lying at the bottom of the jar.
6. Place the lid on the jar and turn it upside down so that the paper clip hangs from the string.
7. Say "abracadabra" and carefully turn the jar right side up so that the paper clip is being pulled by the magnet.

What's happening?

It looks like the paper clip is magically suspended in the air, but actually the string is preventing the paper clip from being pulled all the way to the magnet.

In the real world

• Ferrofluids were invented by NASA as a way to control the flow of liquid fuels in space travel. Today they are used for many other purposes. For example, the military uses it to make aircrafts less visible from enemies' radar systems. It also gives airplanes a better attitude control system.

• A special type of ferrofluid is used in medicine for cancer detection. It is injected and then drawn to possible cancer sites using a strong magnetic field.

  

• It is used to seal things such as computer hard-drives. The fluid of magnetic particles forms a barrier that keep out dust and dirt.

• Research is being done to use ferrofluids to create a light-weight, very flexible clothing which can be transformed into heavy-duty body armor.