course_planning:184_projects:s18_project_13

Thanks to the research that folks at the Hawkion facility were able to do on the EM-boar tigers, the people of Lakeview have been able to set up a scientifically supported protection system. They have installed a giant magnet into the cliffs nearby, and it is aligned in such a way that there is a constant (practically speaking) $5 \text{ mT}$ magnetic field directed into the ground near Lakeview and the surrounding area. The hope is that the field will ward off the EM-boar tigers and keep the people of Lakeview safe.

However, there is a dilemma that has emerged. Local inventor and superstitious person Manny Hallabero is starting to create a fuss around town because he believes the magnetic field is going to destroy his car. He has been driving around with a voltmeter attached to his engine and he claims there is a potential difference across the engine when he's driving fast. Once, he said, there was a potential difference of $0.15 \text{ V}$. He is worried that if the voltage across his engine reaches much higher, it will surely be destroyed and he could end up in danger. Out of the goodness of your heart, you wish to assuage Manny's worries and explain to him why the potential difference exists. You should also provide some guidelines for Manny to make sure he doesn't cause the potential difference to exceed $0.15 \text{ V}$.

Manny's Engine

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 the 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. 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 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. 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. Be as detailed as possible, as Manny can be very stubborn about changing his mind. Dr. Watersa's blueprints, shown below, may be helpful.

Diagram

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
  • course_planning/184_projects/s18_project_13.txt
  • Last modified: 2018/04/12 16:40
  • by dmcpadden