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This Week's Experiment - The Versorium

It is great to be back home, even if just for a couple of days. The shows in
Buffalo went great! I even got in some fossil hunting, thanks to the museum
staff. The shows in Madison, Alabama also went very well. It is always fun
to go back to schools that I have visited in the past and see how much
everyone remembers. The wildlife hike at the Guana refuge was a blast. While
looking at a black racer on the path, the students got a VERY close up look as
it slithered right through the middle of the group to escape. All in all, it
has been a very fun week.

I was digging through my files for the electricity summer camp and came across
this experiment that I thought you would enjoy. Most of us have had
experience with static electricity, even here in humid Florida. While we hear
it crackle when we take the clothes out of the drier (and see if too if the
room is dark. Try it!!), and we feel it when we put our hand near the TV
screen, there are often static charges around us that are too weak for our
senses to detect. The versorium is one way that we can detect them.

For this experiment, you will need:

a plastic soda straw
about 2 feet of thread
tape
objects made of different materials (glass, plastic, wood, etc.)

Tie one end of the thread around the middle of the straw. Use a piece of tape
to secure the other end to the side of a table, so that the straw hangs down
and swings freely. It should not be near the leg of the table. Now, take one
of the objects that you have gathered. A plastic pen is a good place to
start. Rub the pen against a piece of cloth. Now hold it near your hand. Do
you feel anything? Probably not. Now, bring the pen close to the straw and
watch carefully. If you have produced a static charge, then the straw should
swing towards the pen. If it does not, then dry the pen and the cloth with a
hair drier and try it again.

Try lots of different things. Try a pen rubbed with paper, with hair, with
leather, with wood, etc. Try rubbing two pens together. Do two objects made
of the same material produce a static charge?

What is going on? Well, when you rub two different materials together, one
will lose electrons and have a positive charge. The other will gain electrons
and have a negative charge. In some ways, static charges are like magnetic
charges. Two charges that are different will attract. Charges that are the
same will push apart or repel. If you bring a pen that is negatively charged
near the straw that is not charged, something neat happens. The negative
charges in the end of the straw are pushed away (like charges push away),
leaving a positive charge on the end of the straw. Opposite charges attract,
so the positive charge on the end of the straw is pulled towards the negative
charge on the pen.

The versorium does not identify positive and negative charges. Either a
positive or a negative charge will attract the straw. It does show that a
static charge is present, even if it is too weak for our senses to detect. If
you want to try the versorium on a larger scale, tie a rope to a large board.
An 8 foot 2x4 is impressive for this one. Suspend the board, just as you did
with the straw. Once it is balance, blow up a balloon and rub it on your
hair. Bring the balloon near the board and it will swing to the balloon.
Isn't science fun!!!

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Upcoming On-the-road schedule

May 4 - Berryhill School, Milton, FL
May 5 - Science Day, Grace School, Ocala, FL
May 7 - Yulee School, Jacksonville, FL
May 9 - Astronomy Day, Museum of Science and History, Jacksonville, FL
May 11-15 - School shows for FP&L, Ft. Pierce and Stewart, FL
May 16 - Scout extravaganza - NAS, Jacksonville, FL
May 19 - On-line presentation on "Hands-on Science", in American Online's Homefront Hall
June 11 - Green Cove Springs Library, Florida
June 15-20 - American Museum of Science and Energy, Oak Ridge, TN
June 22-26 - Electricity Camp, The Center at Ponte Vedra, FL
June 29-July 3 - Science Wizards Camp, The Center at Ponte Vedra, FL
July 6 - 10 - Crime Busters Camp, The Center at Ponte Vedra, FL
July 13-17 - Dinosaurs Camp, The Center at Ponte Vedra, FL
July 24-27 - Grout Museum, Waterloo, Iowa
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Each week I will e-mail you a new experiment that you can try yourself. I
look for experiments that are unusual, safe, dramatic, cheap, and fun. Since
this list includes teachers, parents, science buffs, and students, I will try
to give you a wide variety of things to try.

Please forward this e-mail to anyone that you think might enjoy it. If you
received this e-mail from someone else and would like to be on the list, just
send me an e-mail at krampf@aol.com, asking to be added to the Experiment of
the Week List. If you ever want off the list, just send me an e-mail
requesting to be removed.

Check out our web site at:
http://members.aol.com/krampf/home.html

for information on:

Watt is Electricity, the million volt electric show
The Nuts and Bolts of Lightning
Burning Questions, the science of fire safety
Educational consulting
Educator workshops

From Robert Krampf's Science Education Company
4850 A1A South
St. Augustine, FL 32084
(904) 471-4578