Van de Graff Generator Cage
Pieces of aluminum foil were attacted by a string and hung
over a cage. That cage was then placed
on top of a van de graff generator which gave the cage a huge negative charge. We
were asked to predict what would happen to the pieces of aluminum foil when the
generator was turned on. We predicted
that when the generator were turned on that both of the pieces of aluminum foil
(inside and outside of the cage) would move away from the cylinder. The answer was that only the pieces of
aluminum foil on the outside of the cage moved away. This is because of shielding; conductors want
to be as far away as possible so that the net charge inside the cage is
zero. It is now known that the electric
field inside a conductor is always zero because of shielding!
Bed of Nails
The bed of nails represented an electric field. When the metal wire was placed on top of the
electric field, the intensity of the field was great. As the metal wire tilted at an angle away
from the bed of nails, the intensity of the electric field got smaller and
smaller until the metal wire and the bed of nails were perpendicular to each
other and the effect of the electric field on the metal wire was zero which
explains why the equation of the flux (The number of electric field lines
through an area) is defined as E A cos (theta).
ActivPhysics
It was concluded that there were 5 lines per charge added
 |
| + 4 Charges |
 |
| +1 Charge |
 |
| -1 Charge |
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| Positive and negative charge |
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