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Unformatted text preview: hrough the three
transformers. 13. An electric field E E0 cos(2 ft ) is applied along the axis of a cylindrical
semiconductor of crosssectional area A=20 cm2 and resistivitym At what
frequency, f, are the amplitudes of the conduction and displacement currents equal? (1
Hz = 1 cycle/s)
A) 5.0 x 109 Hz
B) 4.0 x 103 Hz
C) 2.0 x 1011 Hz
D) 8.0 x 105 Hz
E) 9.0 x 108 Hz Set the amplitudes equal to each other
and solve for f. Version 1 Page 8 14. Two concentric circular loops of wire lie in a plane. The inner loop radius, r = 0.1 m, is
much smaller than the outer loop radius of R = 2 m. What is the approximate mutual
inductance of this configuration of two loops? r A)
B)
C)
D)
E) R Strategy: estimate the flux through the smaller loop by assuming
that the magnetic field at the center of the larger ring is uniform
over the area of the smaller one. Use this flux in the definition of
inductance to calculate inductance. 5.2 x 108 H
8.4 x 107 H
cannot determine without knowing the current in the outer loop
9.9 x 109 H
cannot determine without knowing the rate change of current in the outer loop Note: the mutual inductance is the part of the flux
calculation that does NOT depend on current.
You do not need to know the current to calculate
it. We gave half credit to the two incorrect
NUMERIC answers (A and B on this version). 15. The switch in the circuit below has been closed for a long time. Immediately after
opening the switch wha...
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This document was uploaded on 03/11/2014 for the course PHYSICS 240 at University of Michigan.
 Fall '08
 DaveWinn
 Physics

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