example 6: electric field on disk’s axis z example 2 consider a constant, vertical electric field...
Post on 21-Dec-2015
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Example 6: Electric field on disk’s axis
2
122
32 )(
1
)( cxcx
xdx
ziRz
z
z
zE
22202
ziz
QEzRz
2
04
10,
z
z
z
iEz
iEz
iz
zERz
0
0
0
20
20
2
z
Example 2
Consider a constant, vertical electric field somehow created in a limited region of space. An electron enters the region traveling horizontally with speed . If the region has a length L, how much will the electron be deflected at the end of the region?
0v
Example 3A particle with mass m and charge q is ejected from the lower of two parallel plates with velocity of magnitude as shown. If a constant electric field exists between the plates, magnitude E, where will the particle return to the lower plate? How large must L be so that the particle doesn’t strike the upper plate? (Neglect gravity.)
0v
E
0v
L
x
y
One-dimensional problem:
dxxFWx
x
)(2
1
dx
dUxF )(
dxdx
dUx
x
2
1
)]()([ 12 xUxU
P218 Review: Conservative forces
Two-dimensional problem:
dyFdxFrdFWr
r
y
r
r
x
r
r 2
1
2
1
2
1
)]()([ 12 rUrU
y
UF
x
UF yx
;
veconservatiW does NOT depend on path!
veconservatiW around the closed path is zero!
Have a great day!
Please don’t forget your pictures
Hw: All Chapter 3 problems and exercisesReading: Chapter 3