Data Sheet

-84-
1
3
2
Refrigerator
Door
Project 152
Compass
1. Hold your compass away from everything, notice
that the red arrow always points north. Spin it
around, the red arrow will adjust and resume
pointing north.
The earth’s core is made of iron, which has a
magnetic field. The compass points north because
it is attracted to this magnetic field. This allows
compasses to be used for navigation.
2. Now place the compass next to a large iron object,
such as a refrigerator or car. If the object is heavy
enough, the red arrow will point toward it.
Large iron objects also exert a small magnetic
field, which may attract a nearby compass. The
magnetic field is much weaker than the earth’s, but
much closer to the compass.
3. Now place your magnet near the compass. The
red arrow will immediately point toward the dark
“S” side of the magnet, ignoring a nearby
refrigerator.
Magnets have been induced to have a
concentrated magnetic field at either end. This
magnetic field is much stronger than ordinary iron
objects that may be nearby.
4. Pull out various parts in your kit and from around
your home. Decide which of these you think the
magnet will pick up, then try it and see if you were
right.
The physical properties of iron make it easy to
induce a magnetic attraction in. This doesn’t work
for other metals or other materials.
All materials have tiny particles with electric
charges, but these are so well balanced that
you do not notice them unless an outside
voltage disturbs them. The same tiny particles
also have magnetic charges, which are
usually so well balanced that you do not notice
them unless a magnetic field disturbs them.
Magnets are materials that concentrate their
magnetic charges at opposite ends. One side
attracts while the other repels, but the overall
material is neutral. Most magnets are made
of iron. The name “magnet” comes from
magnetite, an iron ore that magnetism was
first seen in.
The earth we live on is a giant magnet, due to
its iron core. A compass needle always points
north because it is attracted to the earth’s
magnetic field. The opposite ends of a magnet
are often labeled north and south,
representing the north and south poles of the
earth. A compass actually points to the earth’s
magnetic north pole (which is in the Arctic
Ocean just north of Canada), not the
geographic north pole.
SC-3DMEG_Manual.qxp_SC-3Di_Manual_060816 6/19/17 7:34 PM Page 85