The figure shows a cross section of three parallel wires each carrying a current of 5.0 A out of the paper. If the distance R = 6.0 mm, what is the magnitude of the magnetic force on a 2.0-m length of any one of the wires?
a.
2.5 mN
b.
3.3 mN
c.
2.2 mN
d.
2.9 mN
e.
1.7 mN
[Ques. 2] If a = 1.0 cm, b = 3.0 cm, and I = 30 A, what is the magnitude of the magnetic field at point P?
a.
0.62 mT
b.
0.59 mT
c.
0.35 mT
d.
0.31 mT
e.
0.10 mT
[Ques. 3] If a = 2.0 cm, b = 5.0 cm, and I = 20 A, what is the magnitude of the magnetic field at the point P?
a.
4.5
T
b.
7.5
T
c.
9.0
T
d.
6.0
T
e.
3.6
T
[Ques. 4] Three long wires parallel to the x axis carry currents as shown. If I = 20 A, what is the magnitude of the magnetic field at the origin?
a.
37
T
b.
28
T
c.
19
T
d.
47
T
e.
58
T
[Ques. 5] A bolt of lightning strikes the ground 200 m from a 100-turn coil oriented vertically and with the plane of the coil pointing toward the lightning strike. The radius of the coil is 0.800 m and the current in the lightning bolt falls from 6.02 106 A to zero in 10.5 s. What is the voltage induced in the coil over this time period? A question for future electrical engineers: is there any way to get lightning to strike repeatedly at the same point?
[Ques. 6] Starting outside the region with the magnetic field, a single square coil of wire enters, moves across, and then leaves the region with a uniform magnetic field 
perpendicular to the page so that the graph shown below represents the induced emf. The loop moves at constant velocity 
. As seen from above, a counterclockwise emf is regarded as positive. In which direction did the loop move over the plane of the page?
a.
The loop moved from bottom to top.
b.
The loop moved from top to bottom.
c.
The loop moved from left to right.
d.
The loop moved from right to left.
e.
All of these directions of motion will produce the graph of emf vs
t.
[Ques. 7] Starting outside the region with the magnetic field, a single square coil of wire enters, moves across, and then leaves the region with a uniform magnetic field perpendicular to the page so that the graph shown below represents the induced emf. The loop moves at constant velocity . As seen from above, a counterclockwise emf is regarded as positive. In which direction did the loop move over the plane of the page?
a.
The loop moved from bottom to top.
b.
The loop moved from top to bottom.
c.
The loop moved from left to right.
d.
The loop moved from right to left.
e.
All of these directions of motion will produce the graph of emf vs
t.
[Ques. 8] Starting outside the region with the magnetic field, a single square coil of wire moves across the region with a uniform magnetic field perpendicular to the page. The loop moves at constant velocity . As seen from above, a counterclockwise emf is regarded as positive. Roger claims that the graph shown below represents the induced emf. Martin says he's wrong. In which direction did the loop move over the plane of the page, or is Martin correct?
a.
Roger is correct: the loop moved from bottom to top.
b.
Roger is correct: the loop moved from top to bottom.
c.
Roger is correct: the loop moved from left to right.
d.
Roger is correct: the loop moved from right to left.
e.
Martin is correct: none of these directions of motion will produce the graph of emf vs
t.
[Ques. 9] As shown below, a square loop of wire of side a moves through a uniform magnetic field of magnitude B perpendicular to the page at constant velocity directed to the right. Which statement regarding the electric field induced in the wires is correct for the wires at the left and right sides of the loop?
a.
The electric field
is directed upwards in both the right and left sides of the loop.
b.
The electric field
is directed upwards in the right side and downwards in the left side of the loop.
c.
The electric field
is directed upwards in the left side and downwards in the right side of the loop.
d.
The electric field
is directed downwards in both the right and left sides of the loop.
e.
There is no electric field present in any side of the loop.
[Ques. 10] As shown below, a square loop of wire of side a moves through a uniform magnetic field of magnitude B perpendicular to the page at constant velocity directed to the right. Judd says that the emf induced in the loop is zero. Roger claims that it has magnitude B
. Which one, if either, is correct, and why?
a.
Judd, because the magnetic flux through the loop is constant.
b.
Roger, because the magnetic flux through the loop is constant.
c.
Judd, because the magnetic flux through the loop is not constant if
.
d.
Roger, because the magnetic flux through the loop is not constant if
.
e.
Roger, because the magnetic flux through the loop is
B = 0.
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