Static Charge -and- Van de Graaff Generators

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Static Charge-and-Van de Graaff Generators

• What is Static Charge?

Here, we're talking about charge as the
difference in the number of electrons that two
different objects have. When the atoms of one
object give up or lose their electrons, these
electrons end up somewhere else. Another object
picks up or gains these strays. Since electrons
are negatively charged, and protons are
positively charged, an object that has picked up
electrons without picking up protons will have a
negative charge overall. When two objects made
of very different materials are rubbed together,
one will be more likely to give away its
electrons. The other will be more likely to
accept these electrons. The more you rub, the
more electrons jump from one to the other.
The electron got its name when a scientist
noticed particles clinging to what material after
he rubbed it with rabbits fur? (Hint Its Greek
translation is elektron) a. rubber b.
amber c. iron d. aluminium
How do you know it is there?
Once an object has gained electrons, it will want
to return to its neutral state and have just as
many protons as electrons. If enough electrons
jump from your skin to another object at once you
can feel a shock, hear a zap, or see a small
spark. Many times, however, the charge built up
is too small for humans to notice without help.
A tool called a voltmeter can measure how many
more electrons are on object than are on its
neighbour.
Lightening is a large-scale example of electrons
jumping from one place to another. Where does
the extra build up of electrons come from?
a. Rain droplets collide with each other as they
fall, knocking off electrons b. As layers of air
of different temperatures rub together, the
cooler layer donates electrons c. Pockets of
rising moisture lose electrons when hit by
falling ice and sleet d. Clouds bump into each
other, knocking off electrons
Where can you find it?
Large build-ups of electrons can give away their
presence in other ways. Since similar charges
repel each other and opposite charges attract,
you can see negatively charged objects repelling
each other and clinging to positively charged
objects. If you stick two pieces of tape to a
smooth surface, then quickly peel each off, the
electrons on the non-sticky sides of the tape
will try repel each other If you slide down a
plastic playground slide quickly in cotton
clothing, the negative charges on your hair will
repel each other and your hair will stick
up. (For best results, make sure the air is dry)
Number the items below from most likely to donate
electrons (1) to most likely to accept electrons
(7)
Fur
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Van de Graaff generator
The Van de Graaff generator was invented by
Robert J. Van de Graaff in 1929 at Princeton
University. One of the largest can generate 2
million volts (XX electrons) and uses metal
spheres that are each 15 feet across.
Van de graff generators come in all sorts of
sizes and can use similar materials to get the
same job done. They can produce anywhere from
(number) to (number)!
http//www.engr.uky.edu/gedney/courses/ee468/expm
nt/vdg-graph.gif