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PHYSICS 208
EXAM C
November 12, 2009
NAME
(10) 1. A conducting rod of length L = 0.65 m and resistance 2.0 ohms is moved with speed
v = 15 rn/s perpendicular to a magnetic field B = 4.4 x 1 0’ T. The force required to keep the rod
moving at the same velocity is
a. 0; b. 4.3 x 102 N; c. 6.6 x 102 N; d. 6.1 x i0 N
is
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10) 2. A series circuit consists of a 0.55 H inductor with internal resistance 8.0 ohms connected
in series with a 4.0 ohm resistor, a switch, and a 12 V battery. When the switch is closed, what is
the maximum current in the 4 ohm resistor?
a.0.50A;b. 1.OA;c. 1.5A;d.3A
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3:
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12 V
bar magnet is
(10> 3. A circular loop of wire is in the plane of the paper. The north pole of a
The direction of
being moved toward the center of the loop from a position in front of the paper.
the induced current in the ioop is
a. north; b. south; c. clockwise; d. counterclockwise
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(10)4. The direction of the induced current in the rectangular wire is
ation
a. clockwise; b. counterclockwise; c. zero; d. cannot be determined from inform
given
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4 k€
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4
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6
(10) 5. Tripling (times 3) the number of turns of a solenoid of fixed length L causes the selfinductance to
increase
a. decrease by a factor of 3; b. increase by a factor of 3; c. decrease by a factor of 9; d.
by a factor of 9
13
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(30) 6. The long, straight, wire AB shown in the figure carries a current of I 14.0 A. The
rectangular loop whose long edges are parallel to the wire carries a current of 12 5.00 A. Find
the magnitude and direction of the net force exerted on the loop by the magnetic field of the
=
wire.
(Start by deriving the magnetic field. Show all steps clearly.)
13
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B
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F
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7
ç ,LJ4
1
(LTr)
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A
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(20) 7. In the circuit shown in the figure the battery and the inductor have no appreciable internal
resistance and there is no current in the circuit. After the switch is closed, find the readings of
)
2
1 and V
the ammeter (A) and voltmeters (V
a. the instant after the switch is closed
b. after the switch has been closed for a very long time.
(Show all steps clearly.)
Ah crrme.+
1
VA
6
jz—
/‘7
VI
2
v
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