A. Manalaysay – PHY2054, Fall 2004
CHAPTER 16
Since the electrostatic force is a conservative force, we can associate with it a potential
energy.
 the
potential energy between two point charges
.
Note that we can
only define differences in potential energy, thus this equation assumes that PE=0 at r
=infinity.
Notice also that there are no absolute value signs around the q’s… PE is a
scalar, not a vector.
Remember that electric field was defined as the ratio of the force on a particle to its
charge;
Voltage (or Electric Potential)
is defined as the ratio of the electric potential
energy of a particle to its charge:
in which case you can see that a point charge produces a voltage:
 The
voltage produced by a point charge.
And voltage is related to the electric field by:
, which is similar (and you should convince yourself of this) to the work
energy theorem from physics 2053:
.
Can you derive one from the
other?
Capacitance
: Any two conductors, if you place equal and opposite charges on them, will
be at different voltages.
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 Spring '08
 Avery
 Physics, Charge, Electric Potential, Energy, Force, Potential Energy, Electric charge, voltage difference, Capacitor Law

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