Question 1

The reason the north pole of a bar magnet free to rotate points north is because:

Accepted Answer

A)  the south geographic pole of the Earth is the Earth's magnetic north pole.
B)  the south geographic pole of the Earth is the Earth's magnetic south pole.
C)  there is a net accumulation of negative magnetic charge at the Earth's south geographic pole.
D)  there is a net accumulation of positive magnetic charge at the Earth's north geographic pole.
E)  the north geographic pole of the Earth is the Earth's magnetic north pole.F) A) and E)
G) C) and D)

Question 2

A particle (mass = 6.0 mg)  moves with a speed of 4.0 km/s in a direction that makes an angle of 37  °\degree°  above the positive x axis in the xy plane.At the instant it enters a magnetic field of (5.0)  mT it experiences an acceleration of (8.0)  m/s2.What is the charge of the particle?

Accepted Answer

A)  (-4.8  μ\muμ 
C)  
B)  4.0  μ\muμ C
C)  (-4.0 μ\muμ 
C)  
D)  4.8 μ\muμ C
E)  (-5.0  μ\muμ 
C)   F) A) and E)
G) C) and D)

Question 3

A circular loop (radius = 0.50 m)  carries a current of 3.0 A and has unit normal vector of () /3.What is the x component of the torque on this loop when it is placed in a uniform magnetic field of () T?

Accepted Answer

A)  4.7 N . m
B)  3.1 N .m
C)  19 N . m
D)  9.4 N.m
E)  12 N . mF) A) and B)
G) B) and D)

Question 4

The point P lies along the perpendicular bisector of the line connecting two long straight wires S and T that are perpendicular to the page.A set of directions A through H is shown next to the diagram.When the two equal currents in the wires are directed up out of the page, the direction of the magnetic field at P is closest to the direction of:

Accepted Answer

A)  E.
B)  F.
C)  G.
D)  H.
E)  AF) All of the above
G) A) and B)

Question 5

The figure shows the orientation of a rectangular loop consisting of 80 closely wrapped turns each carrying a current I.The magnetic field in the region is ()  mT.The loop can turn about the y axis.If  θ	hetaθ  = 30  °\degree° , a = 0.40 m, b = 0.30 m, and I = 8.0 A, what is the magnitude of the torque exerted on the loop?

Accepted Answer

A)  2.5 N . m
B)  1.5 N . m
C)  3.1 N .m
D)  2.7 N . m
E)  0.34 N. m F) C) and D)
G) None of the above

Question 6

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

Accepted Answer

A)  QVB toward the east
B)  Zero
C)  QVB toward the west
D)  QVB upward
E)  QVB toward the southF) A) and E)
G) B) and C)

Question 7

Bert says that a charged particle in a vacuum can travel in a helix only if a uniform electric field and a uniform magnetic field are both present and both parallel to the axis of the helix.Stuart says that only a magnetic field with a component parallel to the axis of the helix is needed.Which one, if either, is correct, and why?

Accepted Answer

A)  Bert, because the charged particle's velocity can have a vertical component only if an electric field in the vertical direction is present.
B)  Stuart, because a component of velocity in the vertical direction is not changed by a vertical component of a magnetic field.
C)  Bert, because a component of velocity in the vertical direction is changed by a vertical component of a magnetic field.
D)  Stuart, because an electric field in the vertical direction would cause the particle to come to a complete stop.
E)  Neither, because particles cannot move in helical paths in the presence of magnetic and electric fields.F) A) and D)
G) C) and E)

Question 8

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

Accepted Answer

A)  0.65 eV
B)  0.71 eV
C)  0.84 eV
D)  0.54 eV
E)  1.4 eVF) A) and E)
G) None of the above

Question 9

One reason why we know that magnetic fields are not the same as electric fields is because the force exerted on a charge +q:

Accepted Answer

A)  is in opposite directions in electric and magnetic fields.
B)  is in the same direction in electric and magnetic fields.
C)  is parallel to a magnetic field and perpendicular to an electric field.
D)  is parallel to an electric field and perpendicular to a magnetic field.
E)  is zero in both if the charge is not moving.F) All of the above
G) B) and D)

Question 10

You stand near the Earth's equator.A positively charged particle that starts moving parallel to the surface of the Earth in a straight line directed east is initially deflected upwards.If you know there are no electric fields in the vicinity, a possible reason why the particle does not initially acquire a downward component of velocity is because near the equator the magnetic field lines of the Earth are directed:

Accepted Answer

A)  upward.
B)  downward.
C)  from south to north.
D)  from north to south.
E)  from east to west.F) B) and E)
G) A) and E)

Question 11

The boundary shown is that of a uniform magnetic field directed in the positive z direction.An electron enters the magnetic field with a velocity pointing along the x axis and exits 0.63  μ\muμ s later at point A.What is the magnitude of the magnetic field?

Accepted Answer

A)  18  μ\muμ T
B)  14  μ\muμ T
C)  28  μ\muμ T
D)  34  μ\muμ T
E)  227  μ\muμ T F) None of the above
G) A) and E)

Question 12

A current of 4.0 A is maintained in a single circular loop having a circumference of 80 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 20  °\degree° .Determine the magnitude of the torque exerted on the loop by the magnetic forces acting upon it.

Accepted Answer

A)  0.41 N . m
B)  0.14 N . m
C)  0.38 N . m
D)  0.27 N . m
E)  0.77 N .m F) A) and E)
G) B) and C)

Question 13

A particle (q =-4.0  μ\muμ C, m = 5.0 mg)  moves in a uniform magnetic field with a velocity having a magnitude of 2.0 km/s and a direction that is 50  °\degree°  away from that of the magnetic field.The particle is observed to have an acceleration with a magnitude of 5.8 m/s2.What is the magnitude of the magnetic field?

Accepted Answer

A)  5.3 mT
B)  4.9 mT
C)  5.1 mT
D)  4.7 mT
E)  3.6 mT F) A) and B)
G) A) and C)

Question 14

A circular coil (radius = 0.40 m)  has 160 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 0.16 N . m when the current in the coil is 4.0 mA.What is the magnitude of the magnetic field?

Accepted Answer

A)  0.37 T
B)  1.6 T
C)  0.50 T
D)  1.2 T
E)  2.5 TF) None of the above
G) A) and E)

Question 15

An electron moves in a region where the magnetic field is uniform, has a magnitude of 60  μ\muμ T, and points in the positive x direction.At t = 0 the electron has a velocity that has an x component of 30 km/s, a y component of 40 km/s, and a z component of zero.What is the radius of the resulting helical path?

Accepted Answer

A)  4.7 mm
B)  18 mm
C)  3.8 mm
D)  2.8 mm
E)  5.7 mm F) A) and B)
G) A) and C)

Question 16

A physicist claims that she has found a new particle with a mass 200 000 times the mass of the proton (1.67*10-27 kg)  and a charge of 3.20 *10-19 C.If she is correct, such a particle travelling in a circle in a uniform 5.00 T magnetic field at a velocity of 2500 m/s will have a radius of:

Accepted Answer

A)  0.261 m.
B)  0.522 m.
C)  1.04 m.
D)  3.27 m.
E)  3.13 * 1026 m.F) A) and C)
G) A) and E)

Question 17

A charged particle (mass = 4.0  μ\muμ g, charge = 5.0  μ\muμ C)  moves in a region where the only force on it is magnetic.What is the magnitude of the acceleration of the particle at a point where the speed of the particle is 5.0 km/s, the magnitude of the magnetic field is 8.0 mT, and the angle between the direction of the magnetic field and the velocity of the particle is 60 °\degree° ?

Accepted Answer

A)  39 km/s2
B)  43 km/s2
C)  48 km/s2
D)  52 km/s2
E)  25 km/s2 F) A) and D)
G) A) and C)

Question 18

A deuteron is accelerated from rest through a 10-kV potential difference and then moves perpendicularly to a uniform magnetic field with B = 1.6 T.What is the radius of the resulting circular path? (deuteron: m = 3.3 *10-27 kg, q = 1.6*10-19 C)

Accepted Answer

A)  19 mm
B)  13 mm
C)  20 mm
D)  10 mm
E)  9.0 mmF) C) and E)
G) C) and D)

Question 19

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

Accepted Answer

A)  (F-3.0 T) 
B)  +3.0 T
C)  +5.0 T
D)  (-5.0 T) 
E)  +6.0 TF) C) and E)
G) A) and B)

Question 20

An electron moving in the positive x direction experiences a magnetic force in the positive z direction.If Bx = 0, what is the direction of the magnetic field?

Accepted Answer

A)  negative y direction
B)  positive y direction
C)  negative z direction
D)  positive z direction
E)  negative x directionF) B) and C)
G) B) and D)

Exam 8: Magnetic Forces

Correct Answer
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Correct Answer
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Correct Answer
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The reason the north pole of a bar magnet free to rotate points north is because:

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

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

Correct Answer
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Correct Answer
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Correct Answer
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A circular loop (radius = 0.50 m) carries a current of 3.0 A and has unit normal vector of () /3.What is the x component of the torque on this loop when it is placed in a uniform magnetic field of () T?

Correct Answer
verified

A deuteron is accelerated from rest through a 10-kV potential difference and then moves perpendicularly to a uniform magnetic field with B = 1.6 T.What is the radius of the resulting circular path? (deuteron: m = 3.3 10-27 kg, q = 1.610-19 C)

Correct Answer
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Correct Answer
verified

One reason why we know that magnetic fields are not the same as electric fields is because the force exerted on a charge +q:

Correct Answer
verified

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

Correct Answer
verified

A physicist claims that she has found a new particle with a mass 200 000 times the mass of the proton (1.6710-27 kg) and a charge of 3.20 10-19 C.If she is correct, such a particle travelling in a circle in a uniform 5.00 T magnetic field at a velocity of 2500 m/s will have a radius of:

Correct Answer
verified

Correct Answer
verified

Correct Answer
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An electron moving in the positive x direction experiences a magnetic force in the positive z direction.If Bx = 0, what is the direction of the magnetic field?

Correct Answer
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Exam 8: Magnetic Forces

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

The reason the north pole of a bar magnet free to rotate points north is because:

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

A particle (mass = 6.0 mg) moves with a speed of 4.0 km/s in a direction that makes an angle of 37 °\degree° above the positive x axis in the xy plane.At the instant it enters a magnetic field of (5.0) mT it experiences an acceleration of (8.0) m/s2.What is the charge of the particle?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A circular loop (radius = 0.50 m) carries a current of 3.0 A and has unit normal vector of () /3.What is the x component of the torque on this loop when it is placed in a uniform magnetic field of () T?

Correct AnswerverifiedShow Answer

A deuteron is accelerated from rest through a 10-kV potential difference and then moves perpendicularly to a uniform magnetic field with B = 1.6 T.What is the radius of the resulting circular path? (deuteron: m = 3.3 *10-27 kg, q = 1.6*10-19 C)

Correct AnswerverifiedShow Answer

The boundary shown is that of a uniform magnetic field directed in the positive z direction.An electron enters the magnetic field with a velocity pointing along the x axis and exits 0.63 μ\muμ s later at point A.What is the magnitude of the magnetic field?

Correct AnswerverifiedShow Answer

One reason why we know that magnetic fields are not the same as electric fields is because the force exerted on a charge +q:

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

A physicist claims that she has found a new particle with a mass 200 000 times the mass of the proton (1.67*10-27 kg) and a charge of 3.20 *10-19 C.If she is correct, such a particle travelling in a circle in a uniform 5.00 T magnetic field at a velocity of 2500 m/s will have a radius of:

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

An electron moving in the positive x direction experiences a magnetic force in the positive z direction.If Bx = 0, what is the direction of the magnetic field?

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
verified

A deuteron is accelerated from rest through a 10-kV potential difference and then moves perpendicularly to a uniform magnetic field with B = 1.6 T.What is the radius of the resulting circular path? (deuteron: m = 3.3 10-27 kg, q = 1.610-19 C)

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

A physicist claims that she has found a new particle with a mass 200 000 times the mass of the proton (1.6710-27 kg) and a charge of 3.20 10-19 C.If she is correct, such a particle travelling in a circle in a uniform 5.00 T magnetic field at a velocity of 2500 m/s will have a radius of:

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
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