184_projects:f20_project_14 [Projects & Practices in Physics]

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===== Project 14 =====
==== Project 14A: iEngineer iThings ====
Based on your impressive work in Lakeview, the engineers at Orange Tech Company (OTC) have recruited you to help them with a product design. They would like to create an induction charger platform that will work with three products: mePhone, meWatch, and the meToothbrush. The engineers at OTC have a basic set up for the charger platform (shown below), which will plug into a wall outlet with an alternating current of 60 Hz and a peak current of 1.5 A. Inside the charger platform is a coil with 1250 turns and a 7.5 cm radius.

{{ 184_notes:proj3_setup.png?500 }}

They need your help designing the receiver coils in each of their products (mePhone, meWatch, and the meToothbrush). To be able to charge, all the products need an alternating induced voltage. For the mePhone, it requires a peak voltage of 4.7 V. The meWatch requires a peak voltage of 0.88 V. The meToothbrush requires a peak voltage of 3.2 V.

The OTC engineers have asked you to create a report that outlines your design for each of the receiver coils (size, shape, etc.), how the induction charger will work, and graphs of the current in the charging platform and the induced voltage in the receiver coils. Remember, a good solution includes explanations, diagrams, evaluations, and commentary in addition to your calculations. See the Project Write Up Rubric for more details.

<WRAP Info>
=== Learning Goals === 
  * Explain how a current in one coil would induce a current in a second coil. 
  * Use graphs to show both the induced current and charging current
  * Calculate an induced voltage from a changing magnetic flux
</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. But it is not only your team members you find. It is the EM-boar tigers base of operations. More important than rescuing your team members you observed something in their lair that effects the whole of humanity and needs to be communicated immediately. 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>