Chapter 16, Part 1
PHY213, lecture 4
1
Chapter 16
Reading should be 16.6-16.9,
NOT
16.7-16.10
HW set #2 (Due Tuesday, June 23
rd
)
Ch. 16:
CQ-1,3,4,6,7,11
P-1,4,8,15,16,23,26,35,42,46
Ch. 17:
CQ-1,2,4,6,10
P-2,6,14,16,19,33,38,42,44
Electric Energy and Capacitance
Electric Potential Energy
s
The electrostatic force is a
conservative force
s
It is possible to define an electrical
potential energy function with this
force
s
Work done by a conservative force
is equal to the negative of the
change in potential energy
Work and Potential Energy
s
There is a uniform
field between the
two plates
s
As the charge moves
from A to B, work is
done on it
s
W = Fd=q E
x
(x
f
– x
i
)
s
ΔPE = - W
= - q E
x
(x
f
– x
i
)
s
only for a uniform
field
Potential Difference
s
The potential difference between points
A and B is defined as the change in the
potential energy (final value minus
initial value) of a charge q moved from
A to B divided by the size of the charge
s
ΔV = V
B
– V
A
= ΔPE / q
s
Potential difference is
not
the same as
potential energy