nguyen (jmn727) – oldhomework 23 – Turner – (59070)
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001
10.0 points
Given:
A loop with current
I
produces a
magnetic moment
μ ,
as shown below.
μ
Consider the following four configurations
of two loops each,
A
,
B
,
C
, and
D
.
The
placement and current directions of the loops
are shown below. The loops are characterized
by their magnetic moments
μ
.
μ
μ
μ
μ
μ
μ
μ
μ
A
B
C
D
For configurations
A
and
B
, assume that
the two current loops have the same axis and
move freely along the axis. For configurations
C
and
D
, assume that the two current loops
are on in same plane and move freely only in
that plane.
In which case(s) are the current loops at
tracted to oneanother?
1.
A
,
C
correct
2.
A
,
D
3.
A
4.
None of these.
5.
D
6.
B
,
C
7.
B
8.
B
,
D
9.
C
Explanation:
If we consider the magnetic moments as a
small magnets, then opposite poles will at
tract (N and S), and same poles will repel
each other (N and N, S and S). In case of A
and C, opposite poles are facing each other,
so the system is stable.
002
10.0 points
A small magnet of length 6
.
5 cm is placed at
an angle of 70
◦
to the direction of uniform
magnetic field of magnitude 0
.
05 T.
The
observed torque has a magnitude of 0
.
14 N m.
Find the magnetic moment of the magnet.
Correct answer: 2
.
9797 A m
2
.
Explanation:
Let :
θ
= 70
◦
,
B
= 0
.
05 T
,
and
τ
= 0
.
14 N m
.
The magnitude of the torque acting on the
magnet is
τ
=
μ B
sin
θ ,
μ
=
τ
B
sin
θ
=
0
.
14 N m
(0
.
05 T) sin 70
◦
=
2
.
9797 A m
2
.
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 Spring '08
 Turner
 Current, Work, Magnetic Field, Magnetic moment

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