Question 1

An electron is on the z axis moving toward the xy plane but it has not reached that plane yet. At that instant:

Accepted Answer

A)  there is only a true current through the xy plane 
B)  there is only a displacement current through the xy plane 
C)  there are both true and displacement currents through the xy plane 
D)  there is neither a true nor a displacement current through the xy plane 
E)  none of the above are true 
A)  there is only a true current through the xy plane 
B)  there is only a displacement current through the xy plane 
C)  there are both true and displacement currents through the xy plane 
D)  there is neither a true nor a displacement current through the xy plane 
E)  none of the above are true

Question 2

Maxwell's great contribution to electromagnetic theory was his hypothesis that:

Accepted Answer

A)  work is required to move a magnetic pole through a closed path surrounding a current 
B)  a time-varying electric flux acts as a current for purposes of producing a magnetic field 
C)  the speed of light could be determined from simple electrostatic and magnetostatic experiments (finding the values of$\mu$0 and   ) 
D)  the magnetic force on a moving charge particle is perpendicular to both   
E)  magnetism could be explained in terms of circulating currents in atoms 
A)  work is required to move a magnetic pole through a closed path surrounding a current 
B)  a time-varying electric flux acts as a current for purposes of producing a magnetic field 
C)  the speed of light could be determined from simple electrostatic and magnetostatic experiments (finding the values of$\mu$0 and   ) 
D)  the magnetic force on a moving charge particle is perpendicular to both   
E)  magnetism could be explained in terms of circulating currents in atoms

Question 3

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 4

An electron traveling with speed v around a circle of radius r is equivalent to a current of:

Accepted Answer

A)  evr/2 
B)  ev/r 
C)  ev/2 $\pi$r 
D)  2 $\pi$er/v 
E)  2 $\pi$ev/r 
A)  evr/2 
B)  ev/r 
C)  ev/2 $\pi$r 
D)  2 $\pi$er/v 
E)  2 $\pi$ev/r

Question 5

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 6

The spin magnetic dipole moment of an electron:

Accepted Answer

A)  is in the same direction as the spin angular momentum 
B)  is zero 
C)  has an magnitude that depend on the orbital angular momentum 
D)  has a magnitude that depends on the applied magnetic field 
E)  none of the above 
A)  is in the same direction as the spin angular momentum 
B)  is zero 
C)  has an magnitude that depend on the orbital angular momentum 
D)  has a magnitude that depends on the applied magnetic field 
E)  none of the above

Question 7

Which of the following equations can be used, along with a symmetry argument, to calculate the electric field of a point charge?

Accepted Answer

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

Question 8

A 1-$\mu$F capacitor is connected to an emf that is increasing uniformly with time at a rate of 100 V/s. The displacement current between the plates is:

Accepted Answer

A)  0 
B)  1 * 10-8 A 
C)  1 *10-6 A 
D)  1 * 10-4 A 
E)  100 A 
A)  0 
B)  1 * 10-8 A 
C)  1 *10-6 A 
D)  1 * 10-4 A 
E)  100 A

Question 9

A magnetic field   is applied to a paramagnetic substance. In the interior the magnetic field produced by the magnetic dipoles of the substance is:

Accepted Answer

A)  greater than   and in the opposite direction 
B)  less than   and in the opposite direction 
C)  greater than   and in the same direction 
D)  less than   and in the same direction 
E)  the same as   
A)  greater than   and in the opposite direction 
B)  less than   and in the opposite direction 
C)  greater than   and in the same direction 
D)  less than   and in the same direction 
E)  the same as

Question 10

Magnetization vectors in neighboring ferromagnetic domains are:

Accepted Answer

A)  always in opposite directions 
B)  always in the same direction 
C)  always in different directions 
D)  sometimes in different directions and sometimes in the same direction 
E)  sometimes in opposite directions and sometimes in the same direction 
A)  always in opposite directions 
B)  always in the same direction 
C)  always in different directions 
D)  sometimes in different directions and sometimes in the same direction 
E)  sometimes in opposite directions and sometimes in the same direction

Question 11

Magnetic dipole X is fixed and dipole Y 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 move toward or away from X 
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 move toward or away from X

Question 12

A bar magnet is broken in half. Each half is broken in half again, etc. The observation is that each piece has both a north and south pole. This is usually explained by:

Accepted Answer

A)  Ampere's theory that all magnetic phenomena result from electric currents 
B)  our inability to divide the magnet into small enough pieces 
C)  Coulomb's law 
D)  Lenz' law 
E)  conservation of charge 
A)  Ampere's theory that all magnetic phenomena result from electric currents 
B)  our inability to divide the magnet into small enough pieces 
C)  Coulomb's law 
D)  Lenz' law 
E)  conservation of charge

Question 13

The magnetic field lines due to an ordinary bar magnet:

Accepted Answer

A)  form closed curves 
B)  cross one another near the poles 
C)  are more numerous near the N pole than near the S pole 
D)  leave the S pole, loop around the outside of the magnet, and enter the N pole 
E)  none of the above 
A)  form closed curves 
B)  cross one another near the poles 
C)  are more numerous near the N pole than near the S pole 
D)  leave the S pole, loop around the outside of the magnet, and enter the N pole 
E)  none of the above

Question 14

The 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 15

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 16

Two of Maxwell's equations contain an integral over a closed surface. For them the infinitesimal vector area   is always:

Accepted Answer

A)  tangent to the surface 
B)  perpendicular to the surface and pointing outward 
C)  perpendicular to the surface and pointing inward 
D)  tangent to a field line 
E)  perpendicular to a field line 
A)  tangent to the surface 
B)  perpendicular to the surface and pointing outward 
C)  perpendicular to the surface and pointing inward 
D)  tangent to a field line 
E)  perpendicular to a field line

Question 17

The intrinsic magnetic dipole moments of protons and neutrons are much less than that of an electron because:

Accepted Answer

A)  their masses are greater 
B)  their angular momenta are much less 
C)  their angular momenta are much greater 
D)  their charges are much less 
E)  their radii are much less 
A)  their masses are greater 
B)  their angular momenta are much less 
C)  their angular momenta are much greater 
D)  their charges are much less 
E)  their radii are much less

Question 18

Which of the following equations can be used, along with a symmetry argument, to calculate the magnetic field of a long straight wire carrying current?

Accepted Answer

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

Question 19

A positively charged ion, due to a cosmic ray, is headed through Earth's atmosphere toward the center of Earth. Due to Earth's magnetic field, the ion will be deflected:

Accepted Answer

A)  south 
B)  north 
C)  west 
D)  east 
E)  not at all since it is a charge and not a pole 
A)  south 
B)  north 
C)  west 
D)  east 
E)  not at all since it is a charge and not a pole

Question 20

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

Exam 32: Maxwells Equations; Magnetism of Matter

An electron is on the z axis moving toward the xy plane but it has not reached that plane yet. At that instant:

Maxwell's great contribution to electromagnetic theory was his hypothesis that:

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

An electron traveling with speed v around a circle of radius r is equivalent to a current of:

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?

The spin magnetic dipole moment of an electron:

Which of the following equations can be used, along with a symmetry argument, to calculate the electric field of a point charge?

A 1- μ\muμ F capacitor is connected to an emf that is increasing uniformly with time at a rate of 100 V/s. The displacement current between the plates is:

A magnetic field is applied to a paramagnetic substance. In the interior the magnetic field produced by the magnetic dipoles of the substance is:

Magnetization vectors in neighboring ferromagnetic domains are:

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

A bar magnet is broken in half. Each half is broken in half again, etc. The observation is that each piece has both a north and south pole. This is usually explained by:

The magnetic field lines due to an ordinary bar magnet:

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

Lenz' law can explain:

Two of Maxwell's equations contain an integral over a closed surface. For them the infinitesimal vector area is always:

The intrinsic magnetic dipole moments of protons and neutrons are much less than that of an electron because:

Which of the following equations can be used, along with a symmetry argument, to calculate the magnetic field of a long straight wire carrying current?

A positively charged ion, due to a cosmic ray, is headed through Earth's atmosphere toward the center of Earth. Due to Earth's magnetic field, the ion will be deflected:

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.

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Filters

A 1- $\mu$ F capacitor is connected to an emf that is increasing uniformly with time at a rate of 100 V/s. The displacement current between the plates is: