Page 53 - BBC Knowledge - October 2017 IN

!

SAFETY
NOTES
Do not drink ferrofluid!
Rare earth magnets are powerful!
Do not swallow. Do not allow young
children to play with them.
Ferrofluid will stain,
so protect skin
and surfaces.
YOU WILL NEED:
l Ferrofluid (available online)
l Rare earth magnet (these are extremely
strong magnets, usually made out of
neodymium)
l Paper towels and cleaning materials
l Gloves
l A plate, or a large, washable table surface

FUTURISTIC

FERROFLUID

METHOD:
1. Wearing your gloves, pour a little of the ferrofluid onto a plate
or a wipeable table surface (avoid woods that might stain).
2. Place the rare earth magnet underneath the plate or table
and watch the black liquid spring into life. Hedgehog-like spiky
tufts will form directly above the magnet, following its movements
as you slide it around the underside.
3. Blow on it to watch the spikes spin! You can even make
the ferrofluid crawl up surfaces and – if you don’t mind making
a mess – hover the magnet over the surface to see it defy gravity
by ‘dripping’ upwards onto the magnet, transforming it into
an eerily squidgy, slimy black ball.

WHAT’S GOING ON?
A ferrofluid is an oily liquid blended with
microscopic particles of metal. It is combined
with a liquid ‘surfactant’ to prevent clumping.
It forms such crazy shapes in the presence of
a magnet because the metal particles try
to align themselves along the path of
the magnetic field.
You can buy small bottles of ferrofluid online,
or you can try making your own by mixing
a cupful of laser printer toner with a little
cooking oil. Be aware that not all modern laser
printer ink is magnetic, so only try it if you
have some spare. Like black printer ink, all
ferrofluids stain easily, so make sure that you
wear gloves and be careful where you pour it.
You may want to consider putting on an apron.
53
OCTOBER 2017