1 /* Useful functions for drawing Physics 102 figures.
3 * Copyright (C) 2008-2009 W. Trevor King <wking@drexel.edu>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
23 // ---------------------- Charges -------------------------
34 void operator init(pair center=(0,0), real q=1, real radius=2mm, pen outline=currentpen, pen fill=red, Label L="") {
38 this.outline = outline;
43 void draw(picture pic=currentpicture) {
47 pair pLabelSize = 1.2 * (max(picL)-min(picL));
48 path c = scale(radius)*unitcircle;
49 filldraw(picF, c, fill, outline);
52 position = (0,-(radius+pLabelSize.y/2)));
53 add(pic, picF, center);
58 Charge pCharge(pair center=(0,0), real q=1, real radius=2mm, pen outline=currentpen, Label L="")
60 Charge c = Charge(center=center, q=q, radius=radius, outline=outline, L=L, fill=red);
65 Charge nCharge(pair center=(0,0), real q=-1, real radius=2mm, pen outline=currentpen, Label L="")
67 Charge c = Charge(center=center, q=q, radius=radius, outline=outline, L=L, fill=blue);
72 Charge neutralCharge(pair center=(0,0), real radius=2mm, pen outline=currentpen, Label L="")
74 Charge c = Charge(center=center, q=0, radius=radius, outline=outline, L=L, fill=grey);
79 Charge aCharge(pair center=(0,0), real q=1, real radius=2mm, pen outline=currentpen, Label L="")
83 c = pCharge(center, q, radius, outline, L);
85 c = nCharge(center, q, radius, outline, L);
87 c = neutralCharge(center, radius, outline, L);
92 // ---------------------- Vectors -------------------------
95 Vector EField(pair center=(0,0), real mag=5mm, real dir=0, Label L="")
97 Vector v = Vector(center=center, mag=mag, dir=dir, L=L, outline=rgb(1,0.5,0.2)); // orange
102 Vector BField(pair center=(0,0), real mag=5mm, real dir=0, Label L="")
104 Vector v = Vector(center=center, mag=mag, dir=dir, L=L, outline=rgb(0.1,1,0.2)); // green
108 // ---------------------- Forces -------------------------
111 Vector CoulombForce(Charge a, Charge b, Label L="", real scale=1mm, real unit=1mm)
113 pair r = b.center - a.center;
115 mag = ((a.q*b.q)*(scale/length(r))^2)*unit;
117 Vector v = Force(center=b.center, mag=mag, dir=dir, L=L);
121 void CoulombForces(Charge c[], real scale=1mm, real unit=1mm)
125 for (int i=0; i<c.length; i+=1) {
126 for(int j=0; j<c.length; j+=1) {
128 s = "$F_{" + format("%d", i+1) + "," + format("%d", j+1) + "}$";
129 F = CoulombForce(c[i], c[j], L=s, scale=scale, unit=unit);