Unformatted text preview: h 1 because it surrounds more
flux than path 1, but smaller than 3 and 4
because it does not surround all of the flux. 1, then 2 and 4 tie, then 3
4, 1, 3, 2
1, 4, then 2 and 3 tie
1,2, then 3 and 4 tie Version 1 Page 6 11. A solid conductor of radius a is supported by insulating disks on the axis of a conducting
tube with inner radius b and outer radius c as shown in the figure. The central conductor
and the tube carry equal currents in opposite directions. The currents are distributed
uniformly over the cross sections of each conductor. Which one of the following
statements about the magnetic field created by this arrangement is FALSE. A)
E) B is a maximum at r=a.
B=0 for r>c
B decreases to zero as you go from r=b to r=c.
B is proportional to 1/r for r<a
B is proportional to 1/r for a<r<b Version 1 Page 7 12. The AC generator in a hydroelectric power plant supplies a small town with an RMS
current of 4000 A at 120 V rms. At the power plant a 50-to-1 step up transformer is used
prior to high voltage transmission. Near the town a substation has a 100-to-1 step down
transformer and then each house has a nearby 20-to-1 step down transformer to provide a
safe, low voltage. Assuming ideal transformers and no transmission losses what RMS
current must be produced in the AC generator?
Step up A)
HV transmission 20-1 Step down Step down 141 A
1000 A 4000 A rms Remember, N_s < N_p in a
step down transformer. We
have to work backwards
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This document was uploaded on 03/11/2014 for the course PHYSICS 240 at University of Michigan.
- Fall '08