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<DIV><FONT size=2 face=Arial>Hallo Manuel,</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>thank you for your solution. </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Now I have to understand your way to find the lines
of the field.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>With best regards,</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Thomas Söll</FONT></DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=mluque5130@aol.com
href="mailto:mluque5130@aol.com">mluque5130@aol.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=pstricks@tug.org
href="mailto:pstricks@tug.org">pstricks@tug.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, January 17, 2010 10:31
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [pstricks] Re : Elektrostatic
Field</DIV>
<DIV><BR></DIV><FONT color=black size=2 face=arial>
<DIV><FONT size=2><FONT face="Arial, Helvetica, sans-serif">This example draws
only the vectors at selected points.<BR>If nobody gives a complete solution to
trace the lines of electric field, I think I can do it in 2 or 3
weeks...</FONT></FONT><BR></DIV>
<DIV><FONT size=2><FONT
face="Arial, Helvetica, sans-serif"><BR>%%%%%%%%%%%%%%%%%%%%%%<BR><BR>\documentclass{article}<BR>\usepackage{pstricks,multido}<BR>\SpecialCoor<BR>\def\fieldlines{%
<BR> /xP \nx\space
def<BR> /yP \ny\space
def<BR> /r1 xP xA sub dup mul
yP dup mul add sqrt def<BR>
/r2 xP xA add dup mul yP dup mul add sqrt
def<BR>% /V q1 r1
div<BR>% q2 r2
div<BR>% add
def<BR>%
Ex=-dV/dx<BR> /Ex q1 xP xA sub
mul r1 3 exp
div<BR>
q2 xP xA add mul r2 3 exp
div<BR>
add def<BR>%
Ey=-dV/dy<BR> /Ey yP
<BR>
q1 r1 3 exp
div<BR>
q2 r2 3 exp
div<BR>
add mul def<BR> /NormeE Ex dup
mul Ey dup mul add sqrt
def<BR> /uEx Ex NormeE div K
mul def<BR> /uEy Ey NormeE div
K mul
def<BR>}<BR>\begin{document}<BR><BR>\begin{pspicture}(-5,-5)(5,6)<BR>\multido{\nx=-5+0.5}{22}{%<BR>\multido{\ny=-5+0.5}{22}{%<BR>\pstVerb{/q1
1 def<BR> /q2 -0.5 q1 mul
def<BR> /K 1
def<BR> /xA 1.8
def<BR>
\fieldlines}<BR>\rput(\nx,\ny){\psline{->}(0,0)(!uEx
uEy)\psdot(0,0)}<BR>}}<BR>\pscircle*(!xA 0){0.25}\pscircle*(!xA neg
0){0.25}<BR>\end{pspicture}<BR><BR>\begin{pspicture}(-5,-5)(5,6)<BR>\multido{\nx=-5+0.5}{22}{%<BR>\multido{\ny=-5+0.5}{22}{%<BR>\pstVerb{/q1
-1 def<BR> /q2 2 q1 mul
def<BR> /K 1
def<BR> /xA 2.2
def<BR>
\fieldlines}<BR>\rput(\nx,\ny){\psline{->}(0,0)(!uEx
uEy)\psdot(0,0)}<BR>}}<BR>\pscircle*(!xA 0){0.25}\pscircle*(!xA neg
0){0.25}<BR>\end{pspicture}<BR>\end{document}<BR><BR>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<BR></FONT></FONT></DIV>
<DIV style="CLEAR: both"></DIV>
<DIV><FONT size=2><FONT face="Arial, Helvetica, sans-serif"><BR>Yours
sincerely <BR><BR>Manuel<BR></FONT></FONT></DIV>
<DIV><BR></DIV>
<DIV
style="FONT-FAMILY: helvetica,arial; COLOR: black; FONT-SIZE: 10pt">-----E-mail
d'origine-----<BR>De : Thomas Söll 1und1
<Thomas.Soell@onlinehome.de><BR>A : pstricks@tug.org<BR>Envoyé le :
Samedi, 16 Janvier 2010 15:02<BR>Sujet : [pstricks] Elektrostatic
Field<BR><BR>
<DIV id=AOLMsgPart_4_af1f1b42-2be3-4245-8931-87be65f6282b>
<DIV><FONT size=2 face=Arial>Hallo,</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>is it possible to draw the the lines of an
E-Field from the superposition of two radialsymmetric Charges, as in the
picture drawn.</FONT></DIV>
<DIV><FONT size=2 face=Arial>There is one +Q1, the other -0,5*Q1.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Has anyone an idea?</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Thanks for helping.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Thomas Söll<IMG
style="WIDTH: 791px; HEIGHT: 841px"
src="cid:4F7F6AC9F28941C7BC958E01EF43A534@BroPC" width=1254
height=1430></FONT></DIV></DIV><!-- end of AOLMsgPart_4_af1f1b42-2be3-4245-8931-87be65f6282b -->
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