The original source of charge for the electrophorus is the charged
Styrofoam plate. How does this charge come about? What is the
sign of this charge?
(Hint: here is a list of triboelectronegativities
that will help determine the sign of the charge on the Styrofoam plate.)
the flow of electrons to or from the Al plate when it is DOWN on
top of the Styrofoam plate and the bulb is touched. Draw
a diagram indicating charge distributions before and after the hand
contacts the bulb.
describe what happens to electrons when the Al plate is raised in the air
and again touched. Again diagram the charge distribution before and after
contact. How is the up-in-the-air situation different?
examine the Ne bulb during the down-touch, up-touch cycle. Only
one side of the NE bulb SHOULD glow at a time, and this should change
depending on whether the Al plate is up or down. Which side (most
positive or most negative) glows?
down-touch, up-touch cycle can be repeated almost indefinitely or
until the Styrofoam charge leaks away. Since the charge on the Styrofoam
is not "used up," where does the energy to light the bulb repeatedly
come from in this device?
Write a complete description of how the electrophorus works. Use
your description to provide examples to define and explain charge
transfer by friction, contact and induction.
Advanced Question: Arizona
gas pumps have a sticker on them as shown. Explain why.