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--- course_planning:184_projects:s18_project_3 [2018/01/23 17:40] – dmcpadden
+++ course_planning:184_projects:s18_project_3 [2018/01/25 17:42] (current) – dmcpadden
@@ Line 53: / Line 53: @@
   * Use superposition to calculate the electric field at one point (by hand) and at many points (using the computer)
   * Be able to articulate what should go into the calculation loop (and what should go outside the calculation loop)
+</WRAP>
+==== Project 3B: Charge the Line ====
+Everything is getting pretty hairy in the town of Lakeview. The town and surrounding landscape are almost under a constant barrage of storms. The number of deaths due to lightning strikes in Lakeview in one week is larger than the amount the whole world has seen in the last 5 years. Jo Harding, a  crazy local scientist who has had a few run-ins with storms before has an idea of putting up giant metal T's, with the base of the T inserted into the ground to try and stop the townspeople from being struck with lightning. Jo wants the base of the T to be made of wood and the horizontal top of the T to be a metal. Mayor Rachel Wando is up for reelection and is willing to listen to any ideas to stop deaths but ever since the lightning storms started she has been in non-stop meetings in which electric fields are being constantly talked about. Rachel reaches out to her friends at the storm chaser HQ for a model of what the electric field will be for one of these T's after it has been struck by lightning. The code below is the beginnings of your teams work on modeling the electric field from the giant T.
+<code>
+## Creating the scene for the code to run in
+scene.range = 2
+## Constants
+TotalCharge = 15 #C
+pointcharge = TotalCharge/7
+k = 9e9
+vscale = 1e-4
+## Objects
+charge1 = sphere(pos=vec(-3,0,0), Q=pointcharge,  color=color.red,  size=5e-1*vec(1,1,1))
+charge2 = sphere(pos=vec(-2,0,0), Q=pointcharge,  color=color.red,  size=5e-1*vec(1,1,1))
+charge3 = sphere(pos=vec(-1,0,0), Q=pointcharge,  color=color.red,  size=5e-1*vec(1,1,1))
+charge4 = sphere(pos=vec(0,0,0), Q=pointcharge,  color=color.red,  size=5e-1*vec(1,1,1))
+charge5 = sphere(pos=vec(1,0,0), Q=pointcharge,  color=color.red,  size=5e-1*vec(1,1,1))
+charge6 = sphere(pos=vec(2,0,0), Q=pointcharge,  color=color.red,  size=5e-1*vec(1,1,1))
+charge7 = sphere(pos=vec(3,0,0), Q=pointcharge,  color=color.red,  size=5e-1*vec(1,1,1))
+charges = [charge1, charge2, charge3, charge4, charge5, charge6, charge7]
+## Calculation Loop 1
+E = vec(0,0,0)
+point = vec(0,0,0)
+for c in charges:
+    r = point - c.pos
+field = arrow(pos=point, axis=vscale*E, color = color.cyan)
+## Calculation Loop 2
+x = -5
+dx = 0.5
+xmax = 5
+while x<=xmax:
+    theta = 0
+    dtheta = 0.1
+    R = 0
+    while theta < 2*pi:
+        E = vec(0,0,0)
+        point = vec(x, R*sin(theta), R*cos(theta))
+        field = arrow(pos=point, axis = E*vscale, color = color.green)
+        theta += dtheta
+    x+=dx
+</code>
+Complete the program above to first represent the total electric field just to the right and left of the line of charges. Then,  calculate the total electric field surrounding the line of charges.
+<WRAP info>
+===Learning Goals===
+  * Understand what a list (or an array) does in the code and why you would want to use one
+  * Understand how a "for" loop works and how it is similar/different from a "while" loop
+  * Make a model of a line of charge using point charges and be able to describe how you would improve your model
+  * Use superposition to calculate and visualize the electric field around a line of charge
 </WRAP>