Three coplanar parallel straight wires carry equal currents I to the right as shown below. The current in the upper two wires is directed to the right, but the current in the bottom wire is directed to the left. Each pair of wires is a distance a apart. The direction of the magnetic force on the middle wire
a.
is up out of the plane of the wires.
b.
is down into the plane of the wires.
c.
is in the plane of the wires, directed upwards.
d.
is in the plane of the wires, directed downwards
e.
cannot be defined, because there is no magnetic force on the middle wire.
[Ques. 2] Three coplanar parallel straight wires carry equal currents I as shown below. The current in the outer wires is directed to the right, and that in the middle wire is directed to the left. Each pair of wires is a distance a apart. The direction of the magnetic force on the middle wire
a.
is up out of the plane of the wires.
b.
is down into the plane of the wires.
c.
is in the plane of the wires, directed upwards.
d.
is in the plane of the wires, directed downwards
e.
cannot be defined, because there is no magnetic force on the middle wire.
[Ques. 3] Three coplanar parallel straight wires carry equal currents I to the right as shown below. Each pair of wires is a distance a apart. The direction of the magnetic force on the middle wire
a.
is up out of the plane of the wires.
b.
is down into the plane of the wires.
c.
is in the plane of the wires, directed upwards.
d.
is in the plane of the wires, directed downwards
e.
cannot be defined, because there is no magnetic force on the middle wire.
[Ques. 4] A thin infinitely large current sheet lies in the
y-z plane. Current of magnitude
Js per unit length along the
z axis travels in the
y-axis direction, which is up out of the page. Which diagram below correctly represents the direction of the magnetic field on either side of the sheet?
a.
b.
c.
d.
e.
[Ques. 5] A solenoid consists of 100 circular turns of copper wire. Parts of three turns, A, B and C, are shown below.
When a current flows through the coil,
a.
both A and C are repelled by B.
b.
A is attracted to B; C is repelled by B.
c.
neither A nor C is attracted to or repelled by B.
d.
A is repelled by B; C is attracted to B.
e.
both A and C are attracted to B.
[Ques. 6] A long wire lies in a tangle on the surface of a table, as shown below. When a current is run through the wire as shown, the largest component of the magnetic field at X points
a.
into the table.
b.
out of the table.
c.
parallel to the nearest segment of wire.
d.
antiparallel to the nearest segment of wire.
e.
along a circle which has its center at the center of the overall loop.
[Ques. 7] Which diagram correctly shows the magnetic field lines created by a circular current loop in which current flows in the direction shown?
a.
b.
c.
d.
e.
[Ques. 8] The figure shows a cross section of three parallel wires each carrying a current of 24 A. The currents in wires B and C are out of the paper, while that in wire A is into the paper. If the distance R = 5.0 mm, what is the magnitude of the force on a 4.0-m length of wire A?
a.
15 mN
b.
77 mN
c.
59 mN
d.
12 mN
e.
32 mN
[Ques. 9] The figure shows a cross section of three parallel wires each carrying a current of 15 A. The currents in wires A and C are out of the paper, while that in wire B is into the paper. If the distance R = 5.0 mm, what is the magnitude of the force on a 4.0-m length of wire C?
a.
90 mN
b.
54 mN
c.
30 mN
d.
18 mN
e.
36 mN
[Ques. 10] The figure shows a cross section of three parallel wires each carrying a current of 20 A. The currents in wires A and B are out of the paper, while that in wire C is into the paper. If the distance R = 5.0 mm, what is the magnitude of the force on a 2.0-m length of wire A?
a.
23 mN
b.
64 mN
c.
32 mN
d.
46 mN
e.
55 mN
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