Thursday, January 3, 2008

The Electrophorus

My electrophorus is coming along quite well. I still
need to attach the acrylic plate to the base and attach
the handle to the metal plate but that shouldn't take to
long once I get the proper glue. I was able to test the
electrophorus with a makeshift metal plate made out
of aluminum foil attached to cardboard. It was a
success although the aluminum foil plate received
only a small charge. I hope the performance will
improve once I have a proper plate.

The electrophorus is made of a metal plate with an
insulating handle and an insulating material which
sits on a grounded metal plate. The electrophorus
is based on electrostatic induction.










To operate, the base is charged by frictional/contact
electrification.








For our purposes we will assume that
the base receives a negative charge.







After the base is charged the metal plate is placed on
top of the base and the negative charge repels the
electrons in the metal plate so that the negative
charge is furthest away from the base while the
positive charge is closest.









Next we ground the metal plate.










The metal plate has now been charged by electrostatic
induction.










The electrophorus is a valuable tool for demonstrating
the principle of electrostatic inductance. Electrostatic
induction is the basis for many electrostatic generators
such as the Wimshurst machine, the Dirod, and others.

For more information on the electrophorus check out:
http://en.wikipedia.org/wiki/Electrophorus
http://www.youtube.com/watch?v=w7A43NpbzYE&feature=related
http://www.ece.rochester.edu/~jones/demos/electrophorus.html
http://www.engr.uky.edu/~gedney/courses/ee468/expmnt/ephorus.html
http://www.alaska.net/~natnkell/electrophorus.htm

metal plate and handle












the base


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