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--- course_planning:184_projects:s18_project_14 [2018/04/17 16:40] – created dmcpadden
+++ course_planning:184_projects:s18_project_14 [2018/04/19 16:47] (current) – dmcpadden
@@ Line 13: / Line 13: @@
   * Use the right hand rule to check the direction of the induced current.
 </WRAP>
+==== Project 14B: Sending signals ====
+You are able to use your successfully MacGyver'd metal detector to track what the EM-boar tigers have left behind and find your trapped team members. You estimate there is about 1 hour and 50 minutes to figure out a way to send some sort of E&M signal out for rescue before the EM-boar tigers realize that you are planning an escape. (What will that signal be??? You decide.) Due to the sensitivity that EM-boar tigers have to E&M waves, you only have one chance to send the signal before they realize what is happening and close in on the team. You will need to make sure that the attempt will work. You have a small metal ball that can be charged up 1e-6 C without discharging in air. You've found a piston that can shake the ball a total distance of 2cm, but at nearly any frequency you need. Your team decides to create a model of the signal to determine how best to orient the setup, how much charge to dump on the ball, and how quickly to shake it. Your group has already started setting up the code.
+<code>
+GlowScript 2.6 VPython
+## Objects
+charge = sphere(pos = vector(0,0,0), radius = 0.001)
+charge.v = vector(0,0,0)
+## Constants and model parameters
+q = 1e-6
+k = 9e9
+mu = 4*pi*1e-7
+mofpi = mu/(4*pi)
+## Set up time parameters
+t = 0
+dt = 0.1
+## Create list of arrows that encricle the charge
+## Each location has two arrows: one for E and one for B
+N = 20
+theta = 0
+dtheta = 2*pi/N
+R = 0.02
+ArrowList = []
+while theta < 2*pi:
+    Loc = vector(R*cos(theta), R*sin(theta), 0)
+    ArrowList.append([arrow(pos=Loc, axis = vector(0,0,0), color=color.cyan),arrow(pos=Loc, axis = vector(0,0,0), color=color.magenta)])
+    theta += dtheta
+## Calculation loop
+while t < 1000:
+    rate(100)
+    ## Charge should oscillate
+    ## Loop through arrows to make E and B vectors
+    for Arrow in ArrowList:
+        r = Arrow[0].pos - charge.pos
+        E = vector(0,0,0)
+        B = vector(0,0,0)
+        Arrow[0].axis = E
+        Arrow[1].axis = B
+    t = t + dt
+</code>
+<WRAP info>
+=== Learning Goals ===
+  * Make predictions for the electric and magnetic fields from a moving charge over time
+  * Model (using VPython/Glowscript) the electric and magnetic fields from an oscillating charge
+  * Explain the effect of changing a variable on your model of the electric and magnetic fields (i.e., what would you expect to change if you changed the magnitude or sign of the charge)
+</WRAP>