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% Crossed Electric and Magnetic fields
% L. Nobre G.
% 2002
% defaultfont := "putr8r";
% defaultscale := 6.5;
verbatimtex
\documentclass{article}
\usepackage{palatino}
\usepackage{concmath}
\usepackage{ccfonts}
\begin{document}
etex
beginfig(1);
numeric inc, ind, tep, larg, altr, lene;
path efld, velv, arch, auxi;
picture bfld;
pair vpos, cent;
tep = 1cm;
larg = 4;
altr = 3;
lene = larg*tep;
bfld = btex $\times$ etex;
% bfld = thelabel("x",origin);
bfld := bfld shifted -(center bfld);
efld = origin--(lene,0);
for ind = 0 upto altr:
drawarrow efld shifted (0,ind*tep);
endfor;
auxi = efld shifted (0,tep);
for ind = 1 upto altr:
for inc = 1 step 2 until 2*larg:
label( bfld, (0.5*inc*tep,(ind-0.5)*tep) );
endfor;
endfor;
vpos = (tep,0.5tep);
label.lft( btex $\vec{B}$ etex, (0.5tep,(altr-0.5)*tep) );
label.lft( btex $\vec{E}$ etex, origin );
label.top( btex $\vec{v}$ etex, vpos );
% label.lft( "B", (0.5tep,(altr-0.5)*tep) );
% label.lft( "E", origin );
% label.top( "v", vpos );
velv = vpos--((larg-1)*tep,(altr-0.5)*tep);
drawarrow velv;
cent = auxi intersectionpoint velv;
arch = ((fullcircle scaled (altr*tep*0.87)) shifted cent) cutafter velv;
draw arch;
label.rt( btex $\theta$ etex, point 0.5*length arch of arch );
% label.rt( "T", point 0.5*length arch of arch );
endfig;
verbatimtex \end{document} etex
end;
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