Compass - Elenco Electronics Snap Circuits STEM Instruction Manual And Recipe Book

Project 45
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Refrigerator
Door
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 usu-
ally so well balanced that you do not
notice them unless a magnetic field dis-
turbs them.
Magnets are materials that concentrate
their magnetic charges at opposite
ends. One side attracts while the other
repels, but the overall material is neu-
tral. Most magnets are made of iron.
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The name "magnet" comes from mag-
netite, 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 at-
tracted to the earth's magnetic field.
The opposite ends of a magnet are
often labeled north and south, repre-
senting 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.

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.
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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 mag-
netic 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 com-
pass. The red arrow will immediately
point toward the black "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. Tie the magnet to a string and hold it near
the compass. Gently spin the magnet,
and see how the compass needle moves.
5. Pull out a 2-snap wire, a paper clip, the
electrodes, the iron core rod, and the thin
bar. Decide which of these you think the
magnet will pick up, then try it and see if
you were right. Do the same for other ma-
terials in your home.
The physical properties of iron make it
easy to induce a magnetic attraction in.
This doesn't work for other metals or other
materials.
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