Deck 16: Maxwells Equations: Magnetism of Matter

Question 1

The statement that magnetic field lines form closed loops is a direct consequence of:

A) Faraday's law
B) Ampere's law
C) Gauss' law for electricity
D) Gauss' law for magnetism
E) the Lorentz force

Answer 1

Gauss' law for magnetism

Question 2

A magnetic field exists between the plates of a capacitor:

A) always
B) never
C) when the capacitor is fully charged
D) while the capacitor is being charged
E) only when the capacitor is starting to be charged

Answer 2

while the capacitor is being charged

Question 3

Displacement current exists wherever there is:

A) a magnetic field
B) moving charge
C) a changing magnetic field
D) an electric field
E) a changing electric field

Answer 3

a changing electric field

Question 4

One of the Maxwell equations begins with .... The symbol " " means:

A) an infinitesimal displacement of a charge
B) an infinitesimal displacement of a magnetic pole
C) an infinitesimal inductance
D) an infinitesimal surface area
E) none of the above

Question 5

Two of Maxwell's equations contain a path integral on the left side and an area integral on the right. The directions of the infinitesimal path element and infinitesimal area element are:

A) always in the same direction
B) always in opposite directions
C) always perpendicular to each other
D) never perpendicular to each other
E) none of the above

Question 6

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

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

Question 7

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

Question 8

Which of the following equations can be used to show that magnetic field lines form closed loops?

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

Question 9

The magnetic field of Earth is roughly the same as that of a magnetic dipole with a dipole moment of about:

A) 10¹⁷ J/T
B) 10¹⁹ J/T
C) 10²¹ J/T
D) 10²³ J/T
E) 10²⁵ J/T

Question 10

Of the following places one would expect that the horizontal component of the Earth's magnetic field to be largest in:

A) Maine
B) Florida
C) Maryland
D) New York
E) Iowa

Question 11

The polarity of an unmarked magnet can be determined using:

A) a charged glass rod
B) a compass
C) an electroscope
D) another unmarked magnet
E) iron filings

Question 12

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

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 13

If an electron has an orbital angular momentum with magnitude L the magnitude of the orbital contribution to its magnetic dipole moment is given by:

A) eL/m
B) eL/2m
C) 2eL/m
D) mL/e
E) mL/2

Question 14

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

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

Question 15

The magnetic properties of materials stem chiefly from:

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 16

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

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 17

Lenz' law can explain:

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 18

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

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 19

When a permanent magnet is strongly heated:

A) nothing happens
B) it becomes an induced magnet
C) it loses its magnetism
D) its magnetism increases
E) its polarity reverses

Question 20

The behavior of ferromagnetic domains in an applied magnetic field gives rise to:

A) hysteresis
B) ferromagnetism
C) the Curie law
D) a lowering of the Curie temperature
E) Gauss' law for magnetism