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When a charged particle is moving in a static uniform magnetic field


A) there will always be a magnetic force exerted on it, regardless of its direction of motion.
B) there may be a magnetic force exerted on it which will cause its speed to change.
C) there may be a magnetic force exerted on it, but its speed will not change.
D) there may be a magnetic force exerted on it, but its direction of motion will not change.
E) None of the above statements are true.

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Which one of the following statements is correct?


A) When a current-carrying wire is in your right hand, with your thumb in the direction of the current, your fingers point opposite to the direction of the B\vec { B } field lines.
B) When a current-carrying wire is in your right hand, with your thumb in the direction of the current, your fingers point in the direction of the B\vec { B } field lines.
C) When a current-carrying wire is in your left hand, with your thumb in the direction of the current, your fingers point in the direction of the B\vec { B } field lines.

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A long,straight,horizontal wire carries current toward the east.An electron moves toward the east alongside and just south of the wire.What is the direction of the magnetic force exerted on the electron?


A) toward the north
B) toward the south
C) upward
D) downward
E) toward the west.

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A flat circular wire loop lies in a horizontal plane on a table and carries current in a counterclockwise direction when viewed from above.At this point,Earth's B\vec { B } field points to the north and dips below the horizontal.Which side of the coil tends to lift off of the table due to the magnetic torque on the loop?


A) the north side
B) the east side
C) the south side
D) the west side
E) The entire loop lifts straight up.

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A proton moving with a velocity of 4.0 × 104 m/s enters a magnetic field of 0.20 T.If the angle between the velocity of the proton and the direction of the B\vec { B } field is 60°,what is the magnitude of the magnetic force exerted on the proton? (e = 1.60 × 10-19C)


A) 1.8 × 10-15 N
B) 0.60 × 10-15 N
C) 1.1 × 10-15 N
D) 2.2 × 10-15 N

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The B\vec { B } field at point P due to a 2.0-A current through a long,straight,thin wire is 8.0 μT.How far is point P from the wire? (μ0 = 4π × 10-7 T ∙ m/A)


A) 2.0 cm
B) 2.5 cm
C) 4.0 cm
D) 5.0 cm
E) 10 cm

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The B\vec { B } field at a distance of 2 cm from a long straight current-carrying wire is 4 μT.What is the B\vec { B } field at a distance of 1 cm from this wire?


A) 2 μT
B) 4 μT
C) 6 μT
D) 8 μT
E) 10 μT

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A charged particle moving along the +x-axis enters a uniform B\vec { B } field pointing along the +z-axis.A uniform electric field is also present.Due to the combined effect of both fields,the particle does not change its velocity.What is the direction of the electric field?


A) along the -y-axis
B) along the +y-axis
C) along the -x-axis
D) along the +x-axis
E) along the -z-axis

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A flat coil containing 25 identical loops carries 6.4 A of current.When it is placed in a uniform magnetic field of 0.22 T that is oriented parallel to the plane of the coil,the magnetic torque on it is 3.7 N ∙ m. (a)What is the magnetic moment of the coil? (b)What is the area of each loop?

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(a)17 A ∙ ...

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A thin copper rod 1.0 m long has a mass of 0.050 kg and is in a B\vec { B } field of 0.10 T.What minimum current in the rod is needed in order for the magnetic force to balance the force exerted on the rod by Earth?


A) 1.2 A
B) 2.5 A
C) 4.9 A
D) 9.8 A

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The B\vec { B } field due to the current through a long,straight wire is 8.0 μT at a distance of 4.0 cm from the center of the wire.What is the current in the wire? (μ0 = 4π × 10-7 T ∙ m/A)


A) 0.20 A
B) 0.40 A
C) 0.80 A
D) 3.2 A
E) 1.6 A

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In the figure,the two long straight wires are separated by a distance of d=0.40 md = 0.40 \mathrm {~m} The currents are I1I_1 = 1.0 A to the right in the upper wire and I2I _2 = 8.0 A to the left in the lower wire.What are the magnitude and direction of the B\vec { B } field at point P,that is a distance d/2=0.20 md / 2 = 0.20 \mathrm {~m} below the lower wire? (μ0 = 4π × 10-7 T ∙ m/A)  In the figure,the two long straight wires are separated by a distance of  d = 0.40 \mathrm {~m}  The currents are  I_1  = 1.0 A to the right in the upper wire and  I _2  = 8.0 A to the left in the lower wire.What are the magnitude and direction of the  \vec { B }  field at point P,that is a distance  d / 2 = 0.20 \mathrm {~m}  below the lower wire? (μ<sub>0</sub> = 4π × 10<sup>-7</sup> T ∙ m/A)

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An electron moves with a speed of 3.0 × 104 m/s perpendicular to a uniform magnetic field of 0.40 T.What is the magnitude of the magnetic force exerted on the electron? (e = 1.60 × 10-19C)


A) 4.8 × 10-14 N
B) 1.9 × 10-15 N
C) 5 × 10-20 N
D) 2.2 × 10-24 N

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A wire lying in the plane of the page carries a current toward the bottom of the page,as shown in the figure.What is the direction of the magnetic force it exerts on an electron that is moving to the left directly toward the wire,as shown? A wire lying in the plane of the page carries a current toward the bottom of the page,as shown in the figure.What is the direction of the magnetic force it exerts on an electron that is moving to the left directly toward the wire,as shown?   A) straight into the page B) straight out of the page C) directly toward the top of the page D) directly toward the bottom of the page E) directly to the left away from the wire


A) straight into the page
B) straight out of the page
C) directly toward the top of the page
D) directly toward the bottom of the page
E) directly to the left away from the wire

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Which one of the following statements is correct?


A) Earth's geographic north pole is the north pole of Earth's magnetic field.
B) Earth's geographic south pole is the south pole of Earth's magnetic field.
C) The north pole of a magnet points towards Earth's geographic north pole.
D) The north pole of a magnet points towards Earth's geographic south pole.
E) None of the above statements is correct.

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A charged particle moves with a constant speed through a region where a uniform magnetic field is present.If the B\vec { B } field points straight upward,the magnetic force exerted on this particle will be strongest when the particle moves


A) straight upward.
B) straight downward.
C) in a plane parallel to Earth's surface.
D) upward at an angle of 45° above the horizontal.

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An electron traveling toward the magnetic north with speed 400 km/s enters a region where Earth's B\vec { B } field has the magnitude 5.0 × 10-5 T and is directed downward at 45° below horizontal.What magnitude magnetic force is exerted on the electron? (e = 1.60 × 10-19C)

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After landing on an unexplored Klingon planet,Mr.Spock investigates the direction of the magnetic field by firing a beam of electrons in various directions and by recording the following observations: A magnetic force in the northwest direction is exerted on the clectrons moving upward. Electrons moving horizontally toward the north are pushed downward. Electrons moving horizontally toward the southeast are pushed upward. Mr.Spock therefore concludes that the B\vec { B } field at this landing site is in which direction?


A) toward the east
B) toward the northeast
C) toward the southwest
D) toward the southeast
E) toward the west

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A proton,moving in a uniform magnetic field,moves in a circle perpendicular to the B\vec { B } field lines and takes time T for each circle.If the proton's speed tripled,what would now be its time to go around each circle?


A) 9T
B) 3T
C) T
D) T/3
E) T/9

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If a calculated quantity has units of NsCm\frac { \mathrm { N } \cdot \mathrm { s } } { \mathrm { C } \cdot \mathrm { m } } ,that quantity could be


A) an E\vec { E } field.
B) an electric potential.
C) μ0.
D) a B\vec { B } field.
E) a magnetic torque.

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