A metal rod of length L in a region of space where a constant magnetic field points into the page rotates clockwise about an axis through its center at constant angular velocity . While it rotates, the point(s) at highest potential is(are)
a.
A.
b.
B.
c.
C.
d.
D.
e.
A and E.
[Ques. 2] The difference between a DC and an AC generator is that
a.
the DC generator has one unbroken slip ring.
b.
the AC generator has one unbroken slip ring.
c.
the DC generator has one slip ring split in two halves.
d.
the AC generator has one slip ring split in two halves.
e.
the DC generator has two unbroken slip rings.
[Ques. 3] A bar magnet is dropped from above and falls through the loop of wire shown below. The north pole of the bar magnet points downward towards the page as it falls. Which statement is correct?
a.
The current in the loop always flows in a clockwise direction.
b.
The current in the loop always flows in a counterclockwise direction.
c.
The current in the loop flows first in a clockwise, then in a counterclockwise direction.
d.
The current in the loop flows first in a counterclockwise, then in a clockwise direction.
e.
No current flows in the loop because both ends of the magnet move through the loop.
[Ques. 4] A conducting bar of length L rotates with a constant angular speed of +2.0 rad/s about a pivot P at one end, as shown. A uniform magnetic field (magnitude = 0.20 T) is directed into the paper. If L = 0.40 m, what is the potential difference, VA VP?
a.
12 mV
b.
+8.0 mV
c.
8.0 mV
d.
+12 mV
e.
16 mV
[Ques. 5] A conducting bar of length L rotates in a counterclockwise direction with a constant angular speed of +2.0 rad/s about a pivot P at one end, as shown. A uniform magnetic field (magnitude = 0.20 T) is directed into the paper. If L = 0.40 m, what is the potential difference, VA VB?
a.
+24 mV
b.
24 mV
c.
+16 mV
d.
16 mV
e.
+32 mV
[Ques. 6] A bar (L = 80 cm) moves on two frictionless rails, as shown, in a region where the magnetic field is uniform (B = 0.30 T) and into the paper. If v = 50 cm/s and R = 60 m, what is the magnetic force on the moving bar?
a.
0.48 N to the right
b.
0.48 N to the left
c.
0.32 N to the left
d.
0.32 N to the right
e.
None of the above
[Ques. 7] A conducting bar moves as shown near a long wire carrying a constant 50-A current. If a = 4.0 mm, L = 50 cm, and v = 12 m/s, what is the potential difference, VA VB?
a.
+15 mV
b.
15 mV
c.
+20 mV
d.
20 mV
e.
+10 mV
[Ques. 8] A conducting bar moves as shown near a long wire carrying a constant 80-A current. If a = 1.0 mm, b = 20 mm, and v = 5.0 m/s, what is the potential difference, Va Vb?
a.
0.24 mV
b.
+0.24 mV
c.
0.19 mV
d.
+0.19 mV
e.
0.76 mV
[Ques. 9] A rod (length = 10 cm) moves on two horizontal frictionless conducting rails, as shown. The magnetic field in the region is directed perpendicularly to the plane of the rails and is uniform and constant. If a constant force of 0.60 N moves the bar at a constant velocity of 2.0 m/s, what is the current through the 12- load resistor?
a.
0.32 A
b.
0.34 A
c.
0.37 A
d.
0.39 A
e.
0.43 A
[Ques. 10] In the arrangement shown, a conducting bar of negligible resistance slides along horizontal, parallel, frictionless conducting rails connected as shown to a 2.0- resistor. A uniform 1.5-T magnetic field is perpendicular to the plane of the paper. If L = 60 cm, at what rate is thermal energy being generated in the resistor at the instant the speed of the bar is equal to 4.2 m/s?
a.
8.6 W
b.
7.8 W
c.
7.1 W
d.
9.3 W
e.
1.8 W
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