samani (nms654) – H7MagnFields – Avram – (1956)
1
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46
questions.
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before answering.
001
10.0 points
The current in the wire shown in the figure is
20 A.
1 cm
2 cm
P
20 A
Find the net magnetic field at point
P
.
The
permeability
of
free
space
is
4
π
×
10
−
7
T
·
m
/
A.
Answer in units of
μ
T.
002
(part 1 of 2) 10.0 points
Consider the application of the BiotSavart
law
Δ
vector
B
=
μ
0
4
π
I
Δ
vector
ℓ
×
ˆ
r
r
2
.
Consider the magnetic field at O due to the
current segments
B
′
B
+semicircle+
CC
′
. The
length of the linear segments,
B
′
B
=
CC
′
=
d
. The semicircle has a radius
R
.
x
y
I
I
I
180
◦
O
R
B
B
′
C
C
′
A
The magnetic field
B
O
at the origin
O
due
to the current through this path is
1.
out of the page.
2.
into the page.
3.
undetermined, since
B
0
= 0
.
003
(part 2 of 2) 10.0 points
At
O
, the magnitude of the magnetic field
due to the current segments described above
is given by
1.
B
O
=
μ
0
I
2
R
2.
B
O
=
μ
0
I
4
π R
3.
B
O
=
μ
0
I
2
π R
4.
B
O
=
μ
0
I π
4
R
5.
B
O
=
μ
0
I π
2
R
6.
B
O
=
μ
0
I
π R
7.
B
O
= 0
8.
B
O
=
μ
0
I π
R
9.
B
O
=
μ
0
I
4
R
10.
B
O
=
μ
0
I
R
004
10.0 points
The closed loop shown in the figure carries a
current of 20 A in the counterclockwise direc
tion.
The radius of the outer arc is 60 cm
,
that of the inner arc is 40 cm
.
Both arcs ex
tent an angle of 60
◦
.
The permeability of free space is 4
π
×
10
−
7
T m
/
A.
40 cm
C
B
60 cm
D
A
O
60
◦
y
z
Find the component of the magnetic field
at point
O
along the
x
axis.
Answer in units of T .
005
(part 1 of 2) 10.0 points
A closed circuit consists of two semicircles of
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samani (nms654) – H7MagnFields – Avram – (1956)
2
radii 58 cm and 30 cm that are connected by
straight segments, as shown in the figure.
A current of
I
= 6 A flows around this
circuit in the clockwise direction.
The permeability of free space is 4
π
×
10
−
7
T m
/
A.
O
30 cm
58 cm
ˆ
ˆ
k
ˆ
ı
ˆ
ı
is upward
from the paper
I
= 6 A
I
What is the direction of the magnetic field
B
at point
O
.
1.
None of these are true‘.
2.
vector
B
bardbl
vector
B
bardbl
=
−
ˆ
ı
3.
vector
B
bardbl
vector
B
bardbl
= +
ˆ
k
4.
vector
B
bardbl
vector
B
bardbl
= +ˆ
5.
vector
B
bardbl
vector
B
bardbl
= +ˆ
ı
6.
vector
B
bardbl
vector
B
bardbl
=
−
ˆ
k
7.
vector
B
bardbl
vector
B
bardbl
=
−
ˆ
006
(part 2 of 2) 10.0 points
Find the magnitude of the magnetic field at
point at point
O
.
Answer in units of
μ
T.
007
10.0 points
A circular loop of wire of radius
R
= 3
.
98 m
lies in the
xy
plane, centered about the origin.
The loop is carrying a current of
I
= 9
.
04 A
flowing in counterclockwise direction.
Consider two
l
= 1
.
12 mm segments of the
loop: one centered about the positive
x
axis,
the other centered about the positive
y
axis.
Hint:
Use BiotSavart law.
The
permeability
of
free
space
is
1
.
25664
×
10
−
6
Tm
/
A
.
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 Magnetic Field, Avram –

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