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Name: ________________________________________ Code # _________
Summer Session 2008
ID: X
7
UCSD Physics 2B
Practice Exam 4
Magnetism & Induction
READ ME !!!
Helpful Hints:
Do this exam a
few
times.
.. Once without the answers,
Once after seeing the solutions & Once again with your formula sheet
This is a good time to
add
formulas/constants to your sheet.
Remember, this is a
timed
exam.
.. work swiftly so you have time to check your answers.
1. A proton with charge
q
=
e
+
is moving with velocity
v
at an angle of
θ
=
50
°
to the direction of a
magnetic field
B
. The
component
of the resulting
force in the direction of B
is
A.
evB
sin(50º) cos(50º)
C.
zero
B.
evB
sin(50º)
D.
evB
cos(50º)
2. A charged particle is moving horizontally westward with a velocity of
v
=
3.5
×
10
6
m
/
s
in a region
where there is a magnetic field of magnitude
B
=
5.6
×
−
5
T
directed due North. If the particle
experiences a force
F
=
7.8
×
−
16
N
upward (out of the page) what is the
magnitude
and
sign
of the
charge
on the particle?
A.
+
4.9
×
−
5
C
B.
−
4.0
×
−
18
C
C.
+
1.4
×
−
11
C
D.
−
1.2
×
−
14
C
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ID: A
2
3. A long straight wire parallel to the
y
axis carries a current of
I
=
6.3
A
j
8
in a region of uniform
magnetic field
B
=
1.5
T
i
8
. What is the
force per unit length
on the wire?
A.
+
6.3
N
m
k
8
B.
+
9.5
N
m
k
8
C.
−
6.3
N
m
k
8
D.
−
9.5
N
m
k
8
4. Two long, parallel wires are spaced 1.0 m apart in air and each carry a current of 1.0 A. What is the
force per unit length
that each wire exerts on the other?
A.
2
π
×
10
−
6
N
m
B.
2.0
×
−
5
N
m
C.
2.0
×
−
7
N
m
D.
2
×
−
5
N
m
5. A circular 20 turn coil has a radius
r
=
5.0
cm
. What is the magnitude of the coil's
magnetic dipole
moment
when it carries a current of
I
=
2.5
A
?
A.
1.5 A•m
2
B.
0.15 A•m
2
C.
3.9 kA•m
2
D.
0.39 A•m
2
6. A circular 20 turn coil of radius 5.0 cm is so oriented that its axis makes a 30º angle with a uniform
magnetic field of 0.15 T. What is the
torque
on the coil when it carries a current of 2.5 A?
A.
1.5
×
−
3
N
⋅
m
C.
2.9
×
−
2
N
⋅
m
B.
9.4
×
−
3
N
⋅
m
D.
5.1
×
−
2
N
⋅
m
Name: ________________________
ID: A
3
7. A circular loop of wire of radius
a
=
6.0
cm
has
N
=
30 turns and lies in the xy plane. It carries a
current
I
=
5.0
A
. What is the magnitude of the
magnetic field at a point
along the axis
x
=
6.0
cm
from the loop center?
A.
19
μ
T
B.
0.56
m T
C.
0.11
T
D.
56
T
8. Two wires lying in the plane of this page carry equal currents
I
in opposite directions as shown in
the diagram below. What is the
magnetic field
at a point
midway
between the wires?
A.
zero
B.
into the page
C.
out of the page
D.
toward the top or bottom of the page
E.
toward one of the two wires
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ID: A
4
9. A rectangular loop of wire of height
h
= 2.2 m is immersed to a depth
x
= 15 m inside a region of
uniform magnetic field
B
= 3.2 T which is perpendicular to the loop as shown below. If the loop has
a resistance R = 150 Ohms and is pulled out of the field with velocity
v
= 3.3 m/s, what will be the
dissipated power
?
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This note was uploaded on 08/23/2008 for the course PHYS 2b taught by Professor Schuller during the Summer '08 term at UCSD.
 Summer '08
 schuller
 Magnetism

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