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===== Project 12 =====
==== Project 12A: Metal Detector ====
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Dramatic events have occurred all over the world as the stormclouds and alien spacecraft have been repelled by what has been described as reverse Hawkion beams. The breakthrough came when it was realized that you must cross the beams in order to disrupt the alien technology. In Lakeview, life has gotten back to relative normality but the town continues to use the magnetic field in order to keep any remaining boar tigers away. There has been the added bonus that there has been a drastic reduction in car accidents due to the populace being afraid that the magnetic field will destroy their engines. However, tranquility is unsettled when the government agency P.E.R.L. comes to town in order to try and capture a live adult EM Boar Tiger. S.P.A.R.T.A.N force has been tasked with acting as a local guide, as P.E.R.L head into the surrounding forest to complete their investigation. Once deep in the forest, your party is ambushed by boar tigers and several of the team are captured and taken away. The remaining members of the team try to follow the tracks of the Boar Tigers but this becomes impossible after a time. However, you remember hearing from Dr. O'Tallest who did research on the boar tigers that their excrement has a very high percentage of nickel in it (it was the colorful poop that kept on being found all over town). You indicate to the group that you think you can McGyver a metal detector together to track your kidnapped colleagues. You have access to a whole bunch of 12 gauge copper wire, an alternating current power supply that can produce a maximum current of 2 A and has a frequency of 60 Hz, and a voltmeter that will measure an alternating voltage. If the voltmeter measures a voltage bigger than 50 mV, it will sound an alarm. You want to design your metal detector so that if there is not a metal nearby, the voltmeter will be below the threshold; however, if there is a metal nearby, then the measured voltage on the voltmeter will be above the threshold and set off the alarm.
=== Learning Goals ===
* Explain how a metal detector works (be able to explain what happens when a metal is present and not present)
* On a microscopic level, explain what happens to the metal pieces when placed in a magnetic field.
* Make a current vs time graph for the alternating current and for the induced current. Explain any similarities and/or differences in the graphs.
* Use the right hand rule to check the direction of the induced current.
==== Project 12B: Manny's Magnetic Brakes ====
Having dealt with kidnapped colleagues, reunited boar-tiger cubs, and all together just survived the semester, the citizens of Lakeview have now gotten bored. They've decided they definitely need an amusement park full of thrill rides for their town. You and your team have been paired with Manny Hallabero to work on the backup brake system for the "Tower of Doom" ride. Manny has suggested that if all the normal brake systems fail, you can simply put a large magnet in the base of the tower and that will act to slow down the cart (no power source, no moving parts needed!). This seems like a wild idea, but it just might work! Manny has shared some of his initial drawings and data.
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You and your team have been asked to consult by the city of Lakeview, given your reliable expertise. They would like you to create a report that includes: updated drawings (with magnetic field, force, induced current shown), an explanation for how this system would work as a brake for the cart, and the maximum $V_{ind}$ in the cart. Of course, they would also like to know any assumptions you make in your report, any limitations of your findings, and your honest evaluation of whether this would work as a brake system. Remember, a good solution is not just equations and numeric calculations, but will include commentary and discussion of those equations, reflections on what those predictions mean, and the limitations of your solution.
=== Learning Goals ===
* Draw the magnetic field from the bar magnet
* Use the right hand rule to determine the direction of the induced current
* Determine which part of the magnetic field makes the force & use the right hand rule to determine the direction of the magnetic force from the induced current
* Use a graph to determine when/where the largest $V_{ind}$ would occur
* Calculate the $V_{ind}$ using the change in magnetic flux
/*
==== Project 12B: Marty McFly and Magnetite Hill ====
You and your team were just minding your own business and trying to finish up your semester, when out of the blue, you were contacted by the famous time travelers Doc Brown and Marty McFly! Apparently they’ve been stranded in 2021 and need your help to get back to 1985!
The power source in their time machine (which is modeled after a DeLorean sports car) seems to be on the fritz. Doc Brown seems to think that they only need 2 V to get their time machine working again. Marty has suggested wrapping some 12-gauge copper wire 500 times around the DeLorean and then driving it down Magnetite Hill, which has a constant B-field of 10 mT that points straight up out of the ground. Marty has already done some research on Magnetite Hill and provided the graph below, which outlines how the angle of the hill changes with time when he’s driving at a constant 35 mph. However, Doc Brown is very concerned about Marty’s plan - he’s worried that there will be magnetic force on the wire that will crush the DeLorean leaving them stranded in time forever!
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Thus, Doc and Marty have come to you for help. They need to know if Marty’s plan will create the 2 V they need for their time machine without crushing the DeLorean in the process. Remember, a good solution is not just equations and numeric calculations, but will include commentary and discussion of those equations, reflections on what those predictions mean, and the limitations of your solution.
=== Learning Goals ===
* Use a graph to determine when/where the largest $V_{ind}$ would occur
* Calculate the $V_{ind}$ using the change in magnetic flux
* Use the right hand rule to determine the direction of the induced current
* Use the right hand rule to determine the direction of the magnetic force from the induced current
*/