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. 2] 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
[Ques. 3] 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. 4] A conducting rectangular loop of mass M, resistance R, and dimensions a b is allowed to fall from rest through a uniform magnetic field which is perpendicular to the plane of the loop. The loop accelerates until it reaches a terminal speed (before the upper end enters the magnetic field). If a = 2.0 m, B = 6.0 T, R = 40 , and M = 0.60 kg, what is the terminal speed?
a.
1.6 m/s
b.
20 m/s
c.
2.2 m/s
d.
26 m/s
e.
5.3 m/s
[Ques. 5] The coil shown in the figure has 2 turns, a cross-sectional area of 0.20 m2, and a field (parallel to the axis of the coil) with a magnitude given by B = (4.0 + 3.0t2) T, where t is in s. What is the potential difference, VA VC, at t = 3.0 s?
a.
7.2 V
b.
+7.2 V
c.
4.8 V
d.
+4.8 V
e.
12 V
[Ques. 6] A long straight wire is parallel to one edge and is in the plane of a single-turn rectangular loop as shown. If the loop is changing width so that the distance x changes at a constant rate of 4.0 cm/s, what is the magnitude of the emf induced in the loop at an instant when x = 6.0 cm? Let a = 2.0 cm, b = 1.2 m, and I = 30 A.
a.
5.3
V
b.
2.4
V
c.
4.8
V
d.
2.6
V
e.
1.3
V
[Ques. 7] A loop of wire (resistance = 2.0 m) is positioned as shown with respect to a long wire which carries a current. If d = 1.0 cm, D = 6.0 cm, and L = 1.5 m, what current is induced in the loop at an instant when the current in the wire is increasing at a rate of 100 A/s?
a.
34 mA
b.
30 mA
c.
27 mA
d.
38 mA
e.
0.50 mA
[Ques. 8] 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. 9] 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. 10] 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
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