Question 1

Magnetic dipole X is fixed and dipole Y is free to move.Dipole Y will initially:

Accepted Answer

A) move toward X but not rotate 
B) move away from X but not rotate 
C) move toward X and rotate 
D) move away from X and rotate 
E) rotate but not translate 
A) move toward X but not rotate 
B) move away from X but not rotate 
C) move toward X and rotate 
D) move away from X and rotate 
E) rotate but not translate

Question 2

Which of the following equations, along with a symmetry argument, can be used to calculate the magnetic field produced by a uniform time-varying electric field?

Accepted Answer

A)    
B)    
C)    
D)    
E) none of these 
A)    
B)    
C)    
D)    
E) none of these

Question 3

A paramagnetic substance, in an external magnetic field, is thermally isolated.The field is then removed.As a result:

Accepted Answer

A) the magnetic energy of the magnetic dipoles decreases 
B) the temperature of the substance increases 
C) the magnetization decreases, but only slightly 
D) the magnetization reverses direction 
E) none of the above 
A) the magnetic energy of the magnetic dipoles decreases 
B) the temperature of the substance increases 
C) the magnetization decreases, but only slightly 
D) the magnetization reverses direction 
E) none of the above

Question 4

Four closed surfaces are shown, each with circular top and bottom faces and curved sides.The areas Atop and Abot of the top and bottom faces and the magnitudes Btop and Bbot of the uniform magnetic fields through the top and bottom faces are given.The fields are perpendicular to the faces and are either inward or outward.Rank the surfaces according to the magnitude of the magnetic flux through the curved sides, least to greatest.

Accepted Answer

A) 1, 2, 3, 4 
B) 3, 4, 1, 2 
C) 1, 2, 4, 3 
D) 4, 3, 2, 1 
E) 2, 1, 4, 3 
A) 1, 2, 3, 4 
B) 3, 4, 1, 2 
C) 1, 2, 4, 3 
D) 4, 3, 2, 1 
E) 2, 1, 4, 3

Question 5

The diagram shows two small diamagnetic spheres, one near each end of a bar magnet.Which of the following statements is true?

Accepted Answer

A) The force on 1 is toward the magnet and the force on 2 is away from the magnet 
B) The force on 1 is away from the magnet and the force on 2 is away from the magnet 
C) The forces on 1 and 2 are both toward the magnet 
D) The forces on 1 and 2 are both away from the magnet 
E) The magnet does not exert a force on either sphere 
A) The force on 1 is toward the magnet and the force on 2 is away from the magnet 
B) The force on 1 is away from the magnet and the force on 2 is away from the magnet 
C) The forces on 1 and 2 are both toward the magnet 
D) The forces on 1 and 2 are both away from the magnet 
E) The magnet does not exert a force on either sphere

Question 6

Suppose you are looking into one end of a long cylindrical tube in which there is a uniform electric field, pointing away from you.If the magnitude of the field is decreasing with time the field lines of the induced magnetic field are:

Accepted Answer

A) circles 
B) ellipses 
C) straight lines parallel to the electric field 
D) straight lines perpendicular to the electric field 
E) none of the above 
A) circles 
B) ellipses 
C) straight lines parallel to the electric field 
D) straight lines perpendicular to the electric field 
E) none of the above

Question 7

If   is the orbital angular momentum of an electron, the magnetic dipole moment associated with its orbital motion:

Accepted Answer

A) is in the direction of   and has magnitude proportional to L 
B) is opposite to the direction of   and has magnitude proportional to L 
C) is in the direction of   and has magnitude proportional to L2 
D) is opposite to the direction of   and has magnitude proportional to L2 
E) does not depend on   
A) is in the direction of   and has magnitude proportional to L 
B) is opposite to the direction of   and has magnitude proportional to L 
C) is in the direction of   and has magnitude proportional to L2 
D) is opposite to the direction of   and has magnitude proportional to L2 
E) does not depend on

Question 8

Lenz' law can explain:

Accepted Answer

A) paramagnetism only 
B) diamagnetism only 
C) ferromagnetism only 
D) only two of the three types of magnetism 
E) all three of the types of magnetism 
A) paramagnetism only 
B) diamagnetism only 
C) ferromagnetism only 
D) only two of the three types of magnetism 
E) all three of the types of magnetism

Question 9

A 1.2-m radius cylindrical region contains a uniform electric field along the cylinder axis.It is increasing uniformly with time.To obtain a total displacement current of 2.0*10 - 9 A through a cross section of the region, the magnitude of the electric field should change at a rate of:

Accepted Answer

A) 5.0 V/m·s 
B) 12 V/m·s 
C) 37 V/m·s 
D) 50 V/m·s 
E) 4.0 * 107 V/m·s 
A) 5.0 V/m·s 
B) 12 V/m·s 
C) 37 V/m·s 
D) 50 V/m·s 
E) 4.0 * 107 V/m·s

Question 10

The diagram shows the spin angular momentum vectors of two electrons and two protons in the same external magnetic field.The field points upward in the diagram.Rank the situations according to the potential energy, least to greatest.

Accepted Answer

A) 1 and 3 tie, then 2 and 4 tie 
B) 2 and 3 tie, then 1 and 4 tie 
C) 1 and 2 tie, then 3 and 4 tie 
D) 3 and 4 tie, then 1 and 2 tie 
E) all tie 
A) 1 and 3 tie, then 2 and 4 tie 
B) 2 and 3 tie, then 1 and 4 tie 
C) 1 and 2 tie, then 3 and 4 tie 
D) 3 and 4 tie, then 1 and 2 tie 
E) all tie

Question 11

The magnetic properties of materials stem chiefly from:

Accepted Answer

A) particles with north poles 
B) particles with south poles 
C) motions of protons within nuclei 
D) proton spin angular momentum 
E) electron magnetic dipole moments 
A) particles with north poles 
B) particles with south poles 
C) motions of protons within nuclei 
D) proton spin angular momentum 
E) electron magnetic dipole moments

Question 12

A paramagnetic substance is placed in a weak magnetic field and its absolute temperature T is increased.As a result, its magnetization:

Accepted Answer

A) increases in proportion to T 
B) increases in proportion to T2 
C) remains the same 
D) decreases in proportion to 1/T 
E) decreases in proportion to 1/T2 
A) increases in proportion to T 
B) increases in proportion to T2 
C) remains the same 
D) decreases in proportion to 1/T 
E) decreases in proportion to 1/T2

Question 13

If an electron has zero orbital angular momentum, the magnitude of its magnetic dipole moment equals:

Accepted Answer

A) zero 
B) half the Bohr magneton 
C) a Bohr magneton 
D) twice a Bohr magneton 
E) none of these 
A) zero 
B) half the Bohr magneton 
C) a Bohr magneton 
D) twice a Bohr magneton 
E) none of these

Question 14

Two of Maxwell's equations contain a path integral on the left side and an area integral on the right.Suppose the area is the surface of a piece of paper at which you are looking and   is chosen to point toward you.Then, the path integral is:

Accepted Answer

A) clockwise around the circumference of the paper 
B) counterclockwise around the circumference of the paper 
C) from left to right 
D) from right to left 
E) from top to bottom 
A) clockwise around the circumference of the paper 
B) counterclockwise around the circumference of the paper 
C) from left to right 
D) from right to left 
E) from top to bottom

Question 15

Gauss' law for magnetism:

Accepted Answer

A) can be used to find   due to given currents provided there is enough symmetry 
B) is false because there are no magnetic poles 
C) can be used with open surfaces because there are no magnetic poles 
D)   
E) none of the above 
A) can be used to find   due to given currents provided there is enough symmetry 
B) is false because there are no magnetic poles 
C) can be used with open surfaces because there are no magnetic poles 
D)   
E) none of the above

Question 16

One of the crucial facts upon which the Maxwell equations are based is:

Accepted Answer

A) the numerical value of the electron charge 
B) charge is quantized 
C) the numerical value of the charge/mass ratio of the electron 
D) there are three types of magnetic materials 
E) none of the above 
A) the numerical value of the electron charge 
B) charge is quantized 
C) the numerical value of the charge/mass ratio of the electron 
D) there are three types of magnetic materials 
E) none of the above

Question 17

Gauss' law for magnetism,   , tells us:

Accepted Answer

A) the net charge in any given volume 
B) that the line integral of a magnetic field around any closed loop must vanish 
C) the magnetic field of a current element 
D) that magnetic monopoles do not exist 
E) charges must be moving to produce magnetic fields 
A) the net charge in any given volume 
B) that the line integral of a magnetic field around any closed loop must vanish 
C) the magnetic field of a current element 
D) that magnetic monopoles do not exist 
E) charges must be moving to produce magnetic fields

Question 18

The potential energy of a magnetic dipole in an external magnetic field is least when:

Accepted Answer

A) the dipole moment is parallel to the field 
B) the dipole moment is antiparallel to the field 
C) the dipole moment is perpendicular to the field 
D) none of the above (the same energy is associated with all orientations) 
E) none of the above (no energy is associated with the dipole-field interaction) 
A) the dipole moment is parallel to the field 
B) the dipole moment is antiparallel to the field 
C) the dipole moment is perpendicular to the field 
D) none of the above (the same energy is associated with all orientations) 
E) none of the above (no energy is associated with the dipole-field interaction)

Question 19

An unmagnetized steel bar is placed inside a solenoid.As the current in the solenoid is slowly increased from zero to some large value, the magnetization of the bar:

Accepted Answer

A) increases proportionally with the current 
B) remains zero for a while and then increases linearly with any further increase in current 
C) increases with increasing current at first but later is much less affected by it 
D) is unaffected by the current 
E) increases quadratically with the current 
A) increases proportionally with the current 
B) remains zero for a while and then increases linearly with any further increase in current 
C) increases with increasing current at first but later is much less affected by it 
D) is unaffected by the current 
E) increases quadratically with the current

Question 20

The magnitude of the Bohr magneton is about:

Accepted Answer

A) 10-15 J/T 
B) 10-19 J/T 
C) 10-23 J/T 
D) 10-27 J/T 
E) 10-31 J/T 
A) 10-15 J/T 
B) 10-19 J/T 
C) 10-23 J/T 
D) 10-27 J/T 
E) 10-31 J/T

Exam 32: Maxwells Equations; Magnetism of Matter

Magnetic dipole X is fixed and dipole Y is free to move.Dipole Y will initially:

Which of the following equations, along with a symmetry argument, can be used to calculate the magnetic field produced by a uniform time-varying electric field?

A paramagnetic substance, in an external magnetic field, is thermally isolated.The field is then removed.As a result:

The diagram shows two small diamagnetic spheres, one near each end of a bar magnet.Which of the following statements is true?

Suppose you are looking into one end of a long cylindrical tube in which there is a uniform electric field, pointing away from you.If the magnitude of the field is decreasing with time the field lines of the induced magnetic field are:

If is the orbital angular momentum of an electron, the magnetic dipole moment associated with its orbital motion:

Lenz' law can explain:

A 1.2-m radius cylindrical region contains a uniform electric field along the cylinder axis.It is increasing uniformly with time.To obtain a total displacement current of 2.0*10 - 9 A through a cross section of the region, the magnitude of the electric field should change at a rate of:

The diagram shows the spin angular momentum vectors of two electrons and two protons in the same external magnetic field.The field points upward in the diagram.Rank the situations according to the potential energy, least to greatest.

The magnetic properties of materials stem chiefly from:

A paramagnetic substance is placed in a weak magnetic field and its absolute temperature T is increased.As a result, its magnetization:

If an electron has zero orbital angular momentum, the magnitude of its magnetic dipole moment equals:

Two of Maxwell's equations contain a path integral on the left side and an area integral on the right.Suppose the area is the surface of a piece of paper at which you are looking and is chosen to point toward you.Then, the path integral is:

Gauss' law for magnetism:

One of the crucial facts upon which the Maxwell equations are based is:

Gauss' law for magnetism, , tells us:

The potential energy of a magnetic dipole in an external magnetic field is least when:

An unmagnetized steel bar is placed inside a solenoid.As the current in the solenoid is slowly increased from zero to some large value, the magnetization of the bar:

The magnitude of the Bohr magneton is about:

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A 1.2-m radius cylindrical region contains a uniform electric field along the cylinder axis.It is increasing uniformly with time.To obtain a total displacement current of 2.0*10 ^- ⁹A through a cross section of the region, the magnitude of the electric field should change at a rate of: