Solve Faraday's Law: Find Current in Circular Wire

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The discussion revolves around solving for the induced current in a circular wire subjected to a uniform magnetic field and angular motion. Participants explore the application of Faraday's Law, specifically the equation E = -NB(deltaA/deltaT), to find the induced electromotive force (EMF). There is confusion regarding the calculations, particularly in determining the change in area over time and the impact of resistance in the circuit. One user initially miscalculated the resistance, leading to incorrect current values, but later clarified that a 3 Ohm resistor was present, which resolved their confusion. Ultimately, the conversation highlights the importance of accurately accounting for all circuit components when applying Faraday's Law.
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The drawing shows a copper wire (negligible resistance) bent in a circular shape with a radius of .5 m. The radial section BC is fixed in place, while the copper bar AC sweeps around at an angular speed of 15 rad/s. The bar makes electrical contact with the wire at all times. The wire and bar have negligible resistance. A uniform magnetic field exists everywher, is perpendicular to the plane of the circle, and has a magnitude 3.8E-3T. Find the magnitude of the current induced in the loop ABC.

http://edugen.wiley.com/edugen/courses/crs1000/art/qb/6e/ch22p_26.gif

I thought I had done this right but my answer comes out incorrect. I found the equation E=-NB(deltaA/deltaT) using Faraday's Law. I then went about finding the ratio delta A/ Delta T. I took delta A/pi x r^2 = delta t/delta T. This gave delta A/delta t = pi x r^2/T, which I then got wr^2/2 from, so I found that delta A / delta t = wr^2/2.
However, after plugging the numbers in, my answer was incorrect. I asked my instructor, and he said I was right there with the answer, but I'm not sure where else to go or if I need to use different figures since we're using rad/s for the angular velocity. Any help here at all is appreciated.
 
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So what did you get for your answers for the loop voltage (what you call "E") and therefore the current? I get about 7mV and 2.4mA...
 
I got the 7.13 mV but I wasn't sure how to get the current from this since it said the resistance was negligible?
 
There's an explicit 3 Ohm resistor in series with the wire and wiper. You probably just didn't notice it.
 
Oooohhh now I see where the resistance comes from. I was using a number froma different problem somehow. Thanks a lot your answers actually helped me realize what I was doing!
 
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