Data Sheet

Next, hold your magnet near the paper pieces; nothing happens.
Run the comb in your hair again and place it next to the iron filings case; not much
happens (there may be a weak attraction). Now hold the magnet near the iron fil-
ings; they jump to it easily.
What’s happening?
Iron filings are
weakly attracted
to the comb.
Iron filings are
strongly attracted
to the magnet.
Find a comb (or a plastic ruler) and some paper. Rip up the paper
into small pieces. Run the comb through your hair several times
then hold it near the paper pieces to pick them up. You can also
use a pen or plastic ruler, rub it on your clothes (wool works best).
Rubbing the comb through your hair pulls extremely tiny charged
particles from your hair onto the comb. These give the comb a
static electrical charge, which attracts the paper pieces.
Running the comb through your
hair builds up an electric charge
in it, which is different from the
magnetic charge in the magnet.
The paper pieces are attracted
to an electric charge, while the
iron filings are attracted to a
magnetic charge.
You will learn more about the
differences between electricity
and magnetism later.
Notice how your hair can “stand up” or be attracted to the comb when
the air is dry. How will this change if you wet your hair? (Try it.)
Take a piece of newspa-
per or other thin paper
and rub it vigorously with
a sweater or pencil. It will
stick to a wall.
Cut the paper into two
long strips, rub them, then
hang them next to each
other. See if they attract
or repel each other.
If you have two balloons, rub
them to a sweater and then
hang the rubbed sides next
to each other. They repel
away. You could also use
the balloons to pick up tiny
pieces of paper.
Electricity is immensely more powerful than gravity (gravity is what causes
things to fall to the ground when you drop them). However electrical attrac-
tion is so completely balanced out that you don’t notice it, while gravity’s ef-
fects are always apparent because they are not balanced out.
Gravity is actually the attraction between objects due to their weight (or tech-
nically, their mass). This effect is extremely small and can be ignored unless
one of the objects is as big as a planet (like the earth). Gravity attraction
never goes away and is seen every time you drop something. Electrical
charge, though usually balanced out perfectly, can move around and
change quickly.
For example, you have seen how clothes can cling together in the dryer due
to static electricity. There is also a gravity attraction between the sweaters,
but it is always extremely small.
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