A SIMPLE ELECTROSTATIC GENERATOR Bill Beaty The Electrophorus
Cut out a disk of cardboard about 8" to 12" in diameter. Cover one side
with aluminum foil, and fold the foil up over the other side so it
partially covers it. Attach some sort of insulating handle to the center
of the remaining cardboard area (tape a plastic or styrofoam cup to the
cardboard, or glue a small block of styrofoam) When holding the disk by
its handle, the far side of the disk should be entirely covered with foil,
and your fingers on the handle should be some distance away from the foil.
_ | | Handle | | =================== Foil-covered cardboardNext, get an easily-charged object such as a balloon, or a thick plastic sheet, plastic cutting board, styrofoam packing block, etc. Also get something that can be used to electrically charge this object through rubbing, such as a piece of (artificial) fur, a wool sweater, a wig, your hairy head or arms, etc.
You need a low-humidity day to operate the Electrophorus
To test humidity, rub your plastic object with the fur or sweater and see
if it becomes charged and makes the fur stand on end when it's held close
to the charged area on the plastic. If you can't get the plastic object
to raise the fur, wait for a less moist day. Or go into an airconditioned
building and try again. (Or sometimes a warm sweater fresh from the
clothes-dryer will work. But don't use anti-static fabric softener!)
To operate the electrophorus, place your plastic object on a table and rub
its surface with fur or wool to charge it well. Or if your hair is clean
and without grease, try rubbing the object on your head to charge it up.)
Place the cardboard/foil disk upon the charged surface, foil side down.
With the disk still on the plastic, touch the foil to allow it to steal
charge from your body. You'll feel a tiny spark.
\ \ finger \_ \ __\ \ \ _ \\\\_\\\ | | Handle \\ | | Foil-covered cardboard >TOUCH!< =================== |_____________| Styrofoam block
Now, while holding the disk only by the insulating handle, lift it from
the charged surface. The disk is now charged, and it can be used to blink
a small NE-2 neon bulb, or to create small sparks, to deflect an
electroscope leaf, pick up lint, charge a Leyden Jar capacitor, etc.
The plastic object remains fully charged, even though it has been used
to charge the aluminum foil. It need not be rubbed for a while and can be
used again and again to charge the foil plate, since the charging of the
foil DID NOT remove any charge from the plastic surface. This seems
really weird, or even impossible? The charged plastic in this generator
acts more like a magnet than like a source of energy, and it does not lose
its strength when it attracts charge into the foil. But from where does
the electrical energy come? It comes from the work your arm did in
pulling the foildisk away from the plastic surface.
The electrophorus WILL run the Soda
Bottle motor very slowly. (If
humidity is high it will not work.) Connect the foil of one of the
motor's bottles to ground. (water faucets connect to ground, or connect
to the screw on a wall switch cover plate.) Charge the electrophorus disk
and touch it to the OTHER, non-grounded bottle foil of the motor. Do this
over and over fairly fast, and the motor will slowly turn.