An electron has a velocity of {image} in the positive x direction at a point where the magnetic field has the components {image} {image} and {image} What is the magnitude of the acceleration of the electron at this point?

1
An electron has a velocity of image in the
positive x direction at a point where the
magnetic field has the components image image
and image What is the magnitude of the
acceleration of the electron at this point?

1. image
2. image
3. image
4. image
5. image

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2
A particle image moves in a uniform magnetic
field with a velocity having a magnitude of 3.0
km/s and a direction that is image away from
that of the magnetic field. The particle is
observed to have an acceleration with a magnitude
of image What is the magnitude of the magnetic
field?

1. 1.5 mT
2. 6.6 mT
3. 5.9 mT
4. 1.3 mT
5. 4.1 mT

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3
A 6.0-C charge moves with a velocity of (2.0i
4.0j 6.0k) m/s and experiences a magnetic force
of (4.0i - 20j 12k) N. The x component of the
magnetic field is equal to zero. Determine the y
component of the magnetic field.

1. 1.0 T
2. - 1.0 T
3. 5.0 T
4. - 5.0 T
5. - 6.0 T

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4
A particle (mass 1.0 mg, charge image )
moves in the positive direction along the x axis
with a velocity of 3.0 km/s. It enters a magnetic
field of (2.0i 2.0j 3.0k) mT. What is the
acceleration of the particle?

1. image
2. image
3. image
4. image
5. image

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5
A positively charged particle has a velocity in
the positive z direction at point P. The magnetic
force on the particle at this point is in the
positive y direction. Which one of the following
statements about the magnetic field at point P
can be determined from this data?

1. image is positive.
2. image is negative.
3. image is positive.
4. image is negative.
5. image is positive.

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6
A charged particle (mass M, charge Q gt 0)
moves in a region of space where the magnetic
field has a constant magnitude of B and a upward
direction. What is the magnetic force on the
particle at an instant when it is moving
horizontally toward the west with speed V?

1. QVB toward the north
2. QVB toward the east
3. Zero
4. QVB downward
5. QVB toward the south

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7
A 2.0-m wire carries a current of 35 A directed
along the positive x axis in a region where the
magnetic field is uniform and given by B (30i -
70j) mT. What is the resulting magnetic force on
the wire?

1. (- 4.9 k) N
2. ( 4.9 k) N
3. (- 9.8 k) N
4. ( 9.8 k) N
5. ( 0.80 k) N

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8
A segment of wire carries a current of 26 A along
the x axis from x - 1.0 m to x 0 and then
along the y axis from y 0 to y 2.0 m. In this
region of space, the magnetic field is equal to
30 mT in the positive z direction. What is the
magnitude of the force on this segment of wire?

1. 1.7 N
2. 8.3 N
3. 2.7 N
4. 6.2 N
5. 9.3 N

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9
A straight wire of length 80 cm carries a current
of 50 A and makes an angle of image with a
uniform magnetic field. If the force on the wire
is 1.0 N what is the magnitude of B?

1. 25 mT
2. 65 mT
3. 57 mT
4. 33 mT
5. 62 mT

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10
A straight wire of length image carries a
current image in the positive z direction in a
region where the magnetic field is uniform and
specified by image image and image where
image is a constant. What is the magnitude of
the magnetic force on the wire?

1. image
2. image
3. image
4. image
5. image

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11
A current of 3.0 A is maintained in a single
circular loop having a circumference of 90 cm. An
external magnetic field of 2.0 T is directed so
that the angle between the field and the plane of
the loop is image Determine the magnitude of
the torque exerted on the loop by the magnetic
forces acting upon it.

1. image
2. image
3. image
4. image
5. image

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12
What current must be maintained in a square loop
(70 cm on a side) to create a torque of image
about an axis through its center and parallel to
one of its sides when a magnetic field of
magnitude 70 mT is directed at image to the
plane of the loop?

1. 34 A
2. 49 A
3. 71 A
4. 72 A
5. 87 A

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13
A wire (mass 80 g, length 70 cm) is suspended
horizontally by two vertical wires which conduct
a current image as shown in the figure. The
magnetic field in the region is into the paper
and has a magnitude of 80 mT. What is the tension
in either wire? applet

1. 0.53 N
2. 0.76 N
3. 0.75 N
4. 0.32 N
5. 0.50 N

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14
A square loop (L 0.30 m) consists of 60 closely
wrapped turns, each carrying a current of 0.50 A.
The loop is oriented as shown in a uniform
magnetic field of 0.40 T directed in the positive
y direction. What is the magnitude of the torque
on the loop? applet

1. image
2. image
3. image
4. image
5. image

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15
A circular coil (radius 0.30 m) has 190 turns
and is in a uniform magnetic field. When the
orientation of the coil is varied through all
possible positions, the maximum torque on the
coil by magnetic forces is image when the
current in the coil is 5.0 mA. What is the
magnitude of the magnetic field?

1. 0.60 T
2. 0.71 T
3. 1.8 T
4. 1.9 T
5. 2.1 T

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16
A deuteron is accelerated from rest through a
90-kV potential difference and then moves
perpendicularly to a uniform magnetic field with
B 1.7 T. What is the radius of the resulting
circular path? (deuteron image image

1. 36 mm
2. 26 mm
3. 57 mm
4. 28 mm
5. 7.7 mm

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17
A 900-eV electron and a 400-eV electron trapped
in a uniform magnetic field move in circular
paths in a plane perpendicular to the magnetic
field. What is the ratio of the radii of their
orbits?

1. 1.5
2. 2.2
3. 2.4
4. 4.2
5. 2.0

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18
A proton moves around a circular path (radius
1.0 mm) in a uniform 0.25-T magnetic field. What
total distance does this proton travel during a
1.5-s time interval? image image

1. 36 km
2. 77 km
3. 91 km
4. 71 km
5. 3.2 km

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19
A charged particle moves in a region of uniform
magnetic field along a helical path (radius 4.0
cm, pitch 19 cm, period 5.0 ms). What is the
speed of this particle as it moves along this
path?

1. 63 m/s
2. 69 m/s
3. 29 m/s
4. 20 m/s
5. 60 m/s

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20
Two single charged ions moving perpendicularly to
a uniform magnetic field (B 0.5 T) with speeds
of 5,000 km/s follow circular paths that differ
in diameter by 6.0 cm. What is the difference in
the mass of these two ions?

1. image
2. image
3. image
4. image
5. image

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21
What is the radius of curvature of the path of a
1.0-keV proton in a perpendicular magnetic field
of magnitude 0.90 T?

1. 5.1 mm
2. 3.9 mm
3. 1.9 cm
4. 1.5 cm
5. 1.6 cm

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22
An electron moves in a region where the magnetic
field is uniform, has a magnitude of image and
points in the positive x direction. At t 0 the
electron has a velocity that has an x component
of 10 km/s, a y component of 30 km/s, and a z
component of zero. What is the radius of the
resulting helical path?

1. 2.4 mm
2. 5.8 mm
3. 5.4 mm
4. 5.6 mm
5. 11 mm

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23
A proton with a kinetic energy of 0.30 keV
follows a circular path in a region where the
magnetic field is uniform and has a magnitude of
50 mT. What is the radius of this path?

1. 5.0 cm
2. 4.1 cm
3. 7.2 cm
4. 6.6 cm
5. 3.5 cm

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24
A proton is accelerated from rest through a
potential difference of 6.5 kV and then moves
perpendicularly through a uniform 0.40-T magnetic
field. What is the radius of the resulting path?

1. 29 mm
2. 20 mm
3. 82 mm
4. 47 mm
5. 2.2 mm

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25
What is the kinetic energy of an electron that
passes undeflected through perpendicular electric
and magnetic fields if E 4.0 kV/m and B 8.0
mT?

1. 0.71 eV
2. 0.81 eV
3. 0.92 eV
4. 0.38 eV
5. 1.7 eV

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26
A velocity selector uses a fixed electric field
of magnitude E and the magnetic field is varied
to select particles of various energies. If a
magnetic field of magnitude B is used to select a
particle of a certain energy and mass, what
magnitude of magnetic field is needed to select a
particle of equal mass but three times the energy?

1. 0.58 B
2. 0.33 B
3. 3.0 B
4. 1.7 B
5. 2.4 B

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27
One reason why we know that magnetic fields are
not the same as electric fields is because the
force exerted on a charge image _____ .

1. is in opposite directions in electric and
   magnetic fields
2. is in the same direction in electric and magnetic
   fields
3. is parallel to a magnetic field and perpendicular
   to an electric field
4. is parallel to an electric field and
   perpendicular to a magnetic field
5. is zero in both if the charge is not moving

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28
A coaxial cable has an inner cylindrical
conductor surrounded by cylindrical insulation
and an outer cylindrical conducting shell. The
outer shell carries the same current but in the
opposite direction from that in the inner
conductor as shown. The coaxial cable sits in a
uniform magnetic field directed downwards with
respect to the cable. What is the effect of the
field on the cable? applet

1. A net force to the left.
2. A net force to the right.
3. A net force upwards.
4. No net force but a slight shift of the inner
   conductor to the right and the outer conductor to
   the left.
5. No net force but a slight shift of the inner
   conductor to the left and the outer conductor to
   the right.

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29
A straight wire is bent into the shape shown.
Determine the net magnetic force on the wire.
applet

1. zero
2. image in the z direction
3. image in the -z direction
4. image in the -z direction
5. image in the z direction

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30
The north-pole end of a bar magnet is held near a
positively charged piece of plastic. The plastic
is _____.

1. attracted
2. repelled
3. unaffected by the magnet

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31
An electron moves in the plane of this paper
toward the top of the page. A magnetic field is
also in the plane of the page and directed toward
the right. The direction of the magnetic force on
the electron is _____.

1. toward the top of the page
2. toward the bottom of the page
3. toward the left edge of the page
4. toward the right edge of the page
5. upward out of the page
6. downward into the page

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32
A wire carries current in the plane of this paper
toward the top of the page. The wire experiences
a magnetic force toward the right edge of the
page. The direction of the magnetic field causing
this force is _____.

1. in the plane of the page and toward the left edge
2. in the plane of the page and toward the bottom
   edge
3. upward out of the page
4. downward into the page

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33
Rank the magnitudes of the net forces acting on
the rectangular loops shown in the figure below,
from highest to lowest. All loops are identical
and carry the same current. image

1. image
2. image
3. image
4. image
5. image

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34
A charged particle is moving perpendicular to a
magnetic field in a circle with a radius image
The magnitude of the magnetic field is increased.
Compared to the initial radius of the circular
path, the radius of the new path is _____.

1. smaller
2. larger
3. equal in size

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