Ross (jr6585) – Hw14 – Ross – (89251) 1 This print ... - WebPhysics

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001 (part 1 of 4) 10.0 points
The figure below shows a straight cylindrical
coaxial cable of radii a, b, and c in which
equal, uniformly distributed, but antiparallel
currents i exist in the two conductors.
a
i out ⊙
b
c
i in ⊗
O
F
E
D
C
Ross (jr6585) – Hw14 – Ross – (89251) 1
r 1
r 2
r 3
r 4
Which expression gives the magnitude of
the magnetic field in the region r 1 < c (at F)?
1. B(r 1 ) = µ 0 i (r 2 1 − b2 )
2 π r 1 (a 2 − b 2 )
2. B(r 1 ) = µ 0 i r 1
2 π c 2
3. B(r 1 ) = µ 0 i (a 2 + r 2 1 − 2 b2 )
2 π r 1 (a 2 − b 2 )
4. B(r 1 ) = µ 0 i r 1
2 π b 2
5. B(r 1 ) = 0
6. B(r 1 ) = µ 0 i
π r 1
7. B(r 1 ) = µ 0 i (a 2 − r 2 1 )
2 π r 1 (a 2 − b 2 )
8. B(r 1 ) = µ 0 i r 1
2 π a 2
9. B(r 1 ) = µ 0 i (a 2 − b 2 )
2 π r 1 (r 2 1 − b2 )
10. B(r 1 ) = µ 0 i
2 π r 1
002 (part 2 of 4) 10.0 points
Which expression gives the magnitude of the
magnetic field in the region c < r 2 < b (at
E)?
1. B(r 2 ) = µ 0 i
2 π r 2
2. B(r 2 ) = µ 0 i (r 2 2 − b2 )
2 π r 2 (a 2 − b 2 )
3. B(r 2 ) = µ 0 i r 2
2 π a 2
4. B(r 2 ) = µ 0 i (a 2 − b 2 )
2 π r 2 (r 2 2 − b2 )
5. B(r 2 ) = µ 0 i r 2
2 π b 2
6. B(r 2 ) = 0
7. B(r 2 ) = µ 0 i r 2
2 π c 2
8. B(r 2 ) = µ 0 i (a 2 − r 2 2 )
2 π r 2 (a 2 − b 2 )
9. B(r 2 ) = µ 0 i
π r 2
10. B(r 2 ) = µ 0 i (a 2 + r 2 2 − 2 b2 )
2 π r 2 (a 2 − b 2 )
003 (part 3 of 4) 10.0 points
Which expression gives the magnitude of the
magnetic field in the region b < r 3 < a (at
D)?
1. B(r 3 ) = µ 0 i r 3
2 π a 2
2. B(r 3 ) = µ 0 i r 3
2 π c 2
3. B(r 3 ) = µ 0 i (a 2 − r 2 3 )
2 π r 3 (a 2 − b 2 )
4. B(r 3 ) = µ 0 i (a 2 + r 2 3 − 2 b2 )
2 π r 3 (a 2 − b 2 )
5. B(r 3 ) = µ 0 i
2 π r 3
6. B(r 3 ) = µ 0 i r 3
2 π b 2

7. B(r 3 ) = µ 0 i
π r 3
8. B(r 3 ) = 0
9. B(r 3 ) = µ 0 i (r 2 3 − b2 )
2 π r 3 (a 2 − b 2 )
10. B(r 3 ) = µ 0 i (a 2 − b 2 )
2 π r 3 (r 2 3 − b2 )
004 (part 4 of 4) 10.0 points
Which expression gives the magnitude of the
magnetic field in the region r 4 > a (at C)?
Ross (jr6585) – Hw14 – Ross – (89251) 2
z
y
Find the magnitude of each current. Answer
in units of A.
a
θ
x
1. B(r 4 ) = 0
2. B(r 4 ) = µ 0 i
π r 4
3. B(r 4 ) = µ 0 i (a 2 − r4 2)
2 π r 4 (a 2 − b 2 )
4. B(r 4 ) = µ 0 i (a 2 − b 2 )
2 , π r 4 (r4 2 − b2 )
5. B(r 4 ) = µ 0 i (a 2 + r4 2 − 2 b2 )
2 π r 4 (a 2 − b 2 )
6. B(r 4 ) = µ 0 i
2 π r 4
7. B(r 4 ) = µ 0 i r 4
2 π c 2
8. B(r 4 ) = µ 0 i r 4
2 π a 2
9. B(r 4 ) = µ 0 i (r 2 4 − b2 )
2 π r 4 (a 2 − b 2 )
10. B(r 4 ) = µ 0 i r 4
2 π b 2
005 10.0 points
Two long, parallel wires, each having a mass
per unit length of 46.2 g/m, are supported in a
horizontal plane by strings 3.21 cm long, as in
the figure. Each wire carries the same current
I, causing the wires to repel each other so
that the angle between the supporting strings
is 22.53 ◦ .
The acceleration due to gravity is 9.8 m/s 2
and the permeability of free space is 1.25664×
10 −6 T · m/A.
006 10.0 points
A long cylindrical shell has a uniform current
density. The total current flowing through
the shell is 16 mA.
The permeability of free space is
1.25664 × 10 −6 T · m/A.
6 cm
3 cm
The current
is 16 mA .
14 km
•
Find the magnitude of the magnetic field at
a point r 1 = 4.4 cm from the cylindrical axis.
Answer in units of nT.
007 10.0 points
A conductor consists of an infinite number
of adjacent wires, each infinitely long and
carrying a current I (whose direction is out-ofthe-page),
thus forming a conducting plane.
A
C
If there are n wires per unit length, what is

Ross (jr6585) – Hw14 – Ross – (89251) 3
the magnitude of ⃗ B?
1. B = µ 0 I
2. B = 2 µ 0 n I
3. B = µ 0 n I
4. B = µ 0 I
2
5. B = 4 µ 0 I
6. B = 4 µ 0 n I
7. B = µ 0 n I
4
8. B = µ 0 I
4
9. B = 2 µ 0 I
10. B = µ 0 n I
2
008 10.0 points
What current is required in the windings of a
long solenoid that has 1245 turns uniformly
distributed over a length of 0.388 m in order
to produce inside the solenoid a magnetic field
of magnitude 9.52×10 −5 T? The permeablity
of free space is 1.25664×10 −6 T m/A. Answer
in units of mA.