Manual Part 2

49
These effects are caused by electricity. We call this
static electricity because the electrical charges are
static (not moving). When electricity ows (usually
through wires) we call it an electric current. And
electric current ows because of the attraction and
repulsion of the charged particles in conducting
materials that are physically connected.
Atoms are the smallest
amount of matter that can
exist independently in our
world. All materials are made
out of atoms, and they are
really, really tiny. Atoms
contain a central nucleus
(which has a positive electrical
charge) that is surrounded
by tiny electrons (which are
negative electrical charges).
When you rub two materials together, electrons can
move from one material to the other, causing a charge
imbalance; in other words, one material becomes more
negatively charged and the other material becomes
more positively charged. When the materials come in
close contact again, electrons will ow back to their
original material in order to balance things out again.
If you pull two fuzzy sweaters apart in the wintertime,
you’ll likely hear a sound like static on the radio. Like
the thunder that accompanies lightning, this crackling
sound is the sound of electrons traveling through the
air from one sweater to the other. We call this static
electricity.
Static electricity can build up in people too; the shock
you sometimes feel when someone touches you is just
the sensation of electrons owing from their body into
yours. Sometimes the static electricity (or buildup of
electrons) becomes so great that, when it discharges
(or ows into something else), it can produce light and
even re (like lightning).
Project 34 | STATIC ELECTRICITY
Electricity exists everywhere, because electrical charges (electrons and nuclei)
are everywhere. But usually the positive and negative charges are so well
balanced (or nearly equal) that you don’t notice the tiny amount of electrons
jumping around. But under certain conditions, like the dry heat inside your house
in winter, electrical charges can build up in certain materials and sparks can y.
Take off a sweater (wool is best)
and listen for crackling noises. Try
it in a dark room and see if you see
sparks. Compare the effects with
different fabrics (wool, cotton, etc.).
Rub a sweater (wool is best) and
see how it clings to other clothes.
Find clothes that cling together in
the dryer, and try to uncling them.
Note: this project
works best on a cold
dry day. If the weather
is humid, the water
vapor in the air allows
the static electric
charge to dissipate,
and this project
may not work.