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HUMANS AND SPARKS
©1997 William J. Beaty
The Cause, Stopping the Pain, and "Electric People"
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"Static electric" sparks can be irritating and their cause sometimes
mysterious. Most people have encountered painful car-door sparks, as well
as those wintertime sparks from doorknobs and large metal objects. What
causes these? What can be done to stop them?
As children, most of us learn the trick of scuffing our
shoes across the carpet in order to charge our bodies. Then we go to
search for victims to "zap" with our electric fingers. Sparks from
rug-scuffing are familiar. If you scuff your feet on the carpet, you
expect to be zapped by the next doorknob you touch. But why do our
bodies sometimes become charged
from simply walking around?
Actually, no friction or rug-scuffing is required in order to electrically
charge your body. The need for friction is a widespread misconception. While
it's true that the friction will increase the charge-separation process,
friction isn't the cause. Whenever two different insulating surfaces
touch together, opposite charges found within the two surfaces become
separated. Simply walking across certain rugs or plastic flooring
will cause your shoe soles to touch the dissimilar material of the rug.
This is enough to separate the
negatives from the positives and create imbalanced electric charges on
the bottoms of your shoes.
"Static" electricity ( more correctly called "net electric charge" )
appears whenever the normal quantities of positive and negative
electricity in a substance are not perfectly equal. Remember that
everything is made of atoms, and atoms in turn are made of positive and
negative electric charges. In other words, your body is just a collection
of positive and negative electrical particles. Normally the positives
cancel out the negatives, and everything behaves electrically "neutral."
No mysterious sparking. But if you ever end up with more negative than
positive, or with more positive than negative, then you have a
charge-imbalance on your body. You will get zapped the next time you touch
a large metal object.
Exactly how can this imbalance occur? Whenever we walk, the soles of our
shoes steal some negative charge from the floor. We leave behind
electrified positive footprints, and our bodies aquire an overall
imbalance of negatives. (Or sometimes vice versa with the negative and
positive, since polarity is determined by the type of shoe soles and the
type of rug.) After many footsteps, our bodies attain a high level of
electric charge and a high voltage.
Measuring the "Static Electric" Voltage on your Body
Body-voltage can easily rise to
several thousand volts, and the next time you touch someone else... ZAP!,
the imbalanced charge gets shared between you and the other person. The
spark is painful because it's extremely hot. It drills into your skin
like a white-hot needle, creating a microscopic burned area.
NEXT: Part 2: SOLVING THE PROBLEM