Page 1. Make Your Own Electrophorus. Collect ... Build It! 1. Tape the Styrofoam cup to the middle of the plate to act as an insulated handle. 2. Completely cover ...
Make Your Own Electrophorus Collect
• 1 Styrofoam cup • 2 Styrofoam plates • Aluminum foil • Tape • Wool fabric (like an old sweater or sock)
Build It! 1. Tape the Styrofoam cup to the middle of the plate to act as an insulated handle. 2. Completely cover the bottom of this plate in aluminum foil, wrapping some foil up around the edges to the top. Tape in place, if necessary. 3. To make the bottom of the electrophorus, tape a Styrofoam plate to the table.
Test It! 4. Rub the bottom plate with wool fabric for one minute. 5. Using the cup handle, pick up the foil-covered plate. Put the foil-covered plate on top of the plate on the table so that the foil is sandwiched between the two plates. 6. Touch the aluminum foil. What happens? 7. Use the cup handle to lift the top of the electrophorus at least 1 foot above the other plate. 8. Touch the aluminum foil again. What happens? 9. Repeat steps 4 and 5 for as long as you would like to. If it stops working, recharge the bottom Styrofoam plate by rubbing it with the wool again. See if you can spot a spark if you darken the room and bring your finger slowly toward the metal.
What’s Happening? An electrophorus is a device that carries an electric charge. By rubbing the wool against the Styrofoam plate, tiny, negatively-charged particles, called electrons, come off the wool and are left on the plate. Styrofoam is an insulator, a material that doesn’t let electrical charge pass through it, so the extra electrons are stuck on the plate, giving it a negative electric charge. However, aluminum foil is a conductor, a material that does allow electrons to move through it. The negative charge on the plate pushes the electrons in the foil away, and when you bring your hand near, some of the electrons jump to your hand, and you feel a shock! After the negative charge is transferred from the foil to your body, the aluminum foil is left with a positive charge. When you touch it again, electrons from your body jump into the aluminum foil, and you feel another shock. This process can be repeated over and over, as long as the Styrofoam plate still has negative charge on it from being rubbed by the wool.
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