course_planning:184_projects:f18_project_12 [Projects & Practices in Physics]

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===== Project 12 =====

==== Project 12A: Clean Source of Energy or Hidden Stash of Jellybeans??? ====

{{ 184_notes:13a_picture.png?700 |Alternative Energy Source}}

The people of Lakeview are starting to get used to living life in the magnetic field, now that it seems to be doing a pretty good job keeping EM-boar tigers from entering into the center of town and causing mayhem. Local alternative energy scientist Alysson Watersa has even installed a source of clean energy that is made possible by the magnetic field. This could be incredibly useful if anything happens to the powerplant. She has constructed a water mill with her bare hands and situated it into the side of the cliff, conveniently below a waterfall so that the motion of the water turns the mill at a frequency of $15 \text{ rpm}$. Dr. Watersa also fixed a board along the axle of the mill, and she has laid a loop of 12-Gauge copper wire (with a radius of $1 \text{ m}$) on the board. One end of the loop becomes a wire that comes out the side of the board and is grounded into the cliff. The other end of the loop becomes a wire that runs out the other side of the mill, all the way back to Lakeview. As the mill turns, so does the loop, causing a current to exist in the wire, which can be used as a small convenience for the good people of Lakeview.

Unfortunately, local superstitious person Manny Hallabero is causing a ruckus again, this time about the new energy source. He claims that it's all hocus pocus, and Dr. Watersa is just using the water mill as a ploy to hide her stash of jellybeans in the face of the cliff in order to avoid sharing. Clearly deluded, he won't listen to Dr. Watersa for even a second, so it's up to you to explain to Manny how the water mill works and why it produces the current that it does. It may be helpful for Manny to see a diagram of the mill and a graph of the current produced as his special type of crazy his often open to representational data. Be as detailed as possible, as Manny can be very stubborn about changing his mind. Dr. Watersa's blueprints, shown below, may be helpful.

{{ 184_notes:13a_representation.png?600 |Diagram}}

<WRAP info>
=== Learning Goals ===
  * Calculate the induced current from a changing magnetic flux
  * Use the right hand rule to determine the direction of the induced current
  * Explain why induced current is different from the current in a circuit (in other words, what does it mean for a current to be "induced"?)
  * Explain why there is a negative sign in Faraday's Law
</WRAP>