Deck 14: Magnetism

Question 1

The earth's geographic North Pole has ______________ magnetic polarity.

Answer 1

south

Question 2

Maxwell proved that electromagnetic phenomena travel in ______________ at the speed of light.

Answer 2

waves

Question 3

The entire group of magnetic field lines, which can be considered flowing outward from the north pole of a magnet, is called magnetic ______________.

Answer 3

flux

Question 4

Flux ______________ is the number of magnetic field lines per unit area of a section perpendicular to the direction of flux.

Question 5

One weber per square meter is called a ______________.

Question 6

The electric or magnetic effect of one body on another without any physical contact between them is called ______________.

Question 7

The ability to concentrate magnetic flux is called ______________.

Question 8

A(n) ______________ needs current from an external source to maintain its magnetic field.

Question 9

A ______________ is a switch with contacts that are opened or closed by an electromagnet.

Question 10

______________ field lines are unaffected by nonmagnetic materials such as air, paper, or plastics.

Question 11

What are the base units for permeability?

A) Maxwell
B) Tesla
C) Weber
D) There are none

Question 12

What maintains the strength of the permanent magnet as it becomes magnetized by induction to form a closed loop?

A) Ferrite
B) Horseshoe
C) Keeper
D) Solenoid

Question 13

What are the two classes of magnets?

A) Permanent and temporary
B) Temporary and electromagnet
C) Copper and nickel
D) Permanent and electromagnet

Question 14

The wire wrapped in a form of a coil that causes the magnetic field to become more concentrated in an electromagnet is referred to as a(n)

A) magnet
B) relay
C) solenoid
D) armature

Question 15

What is the device that is basically a switch with contacts that are opened or closed by an electromagnet?

A) Compass
B) Relay
C) Solenoid
D) Tape recorder

Question 16

The point at which a magnetic material loses its ferromagnetic properties is the

A) Kelvin temperature
B) Centigrade temperature
C) Curie temperature
D) Gilbert temperature

Question 17

In terms of molecular structure, iron atoms are grouped in microscopically small arrangements called

A) ferrites
B) fields
C) dipoles
D) domains

Question 18

What device concentrates the magnetic field of the current in a wire and serves as a simple RF choke?

A) Ferrite core
B) Ferrite rod
C) Ferrite bead
D) Ferrite coil

Question 19

Preventing one component from affecting another through their common electric or magnetic field is called

A) blocking
B) shielding
C) covering
D) filtering

Question 20

The best shield for a component in a steady magnetic field is a

A) good magnetic material
B) diamagnetic material
C) housing made of aluminum
D) housing made of copper

Question 21

When a wire carrying current is placed in an applied magnetic field, a voltage across the wire is created that is proportional to the strength of the magnetic field is

A) the Hall effect
B) Gilbert's magnetic theorem
C) Maxwell's law
D) the Tesla effect

Question 22

Which of the following is not a nonmagnetic material?

A) Paper
B) Glass
C) Wood
D) Cobalt

Question 23

One maxwell unit equals

A) one magnetic field line
B) 1 x 10⁸ line
C) 0.001 weber
D) 50 ?Wb

Question 24

One weber equals

A) one magnetic field line
B) 1 x 10⁸ line
C) 0.001 maxwells
D) 50 ?Mx

Question 25

In the cgs system, the unit that is one line per square centimeter is

A) flux density
B) maxwell
C) gilbert
D) gauss

Question 26

One weber per square meter is called

A) tesla
B) maxwell
C) gilbert
D) gauss

Question 27

The tesla is equal to

A) 1 x 10⁴ G
B) 1 x 10⁸ G
C) one gilbert per square meter
D) 200 G

Question 28

What magnetic effect is at the heart of such technologies as antilock brake sensors and some keyboards?

A) Tesla effect
B) Gauss effect
C) Maxwell effect
D) Hall effect

Question 29

Every magnet has both a north and a south pole.

Question 30

Like magnetic poles attract each other and unlike poles repel.

Question 31

Every magnet has invisible magnetic field lines that extend outward from the magnetic poles.

Question 32

The magnet can be considered the generator of an external magnetic field, provided by the two opposite magnetic poles at the ends.

Question 33

Magnetic field lines are affected by air, paper, glass, and wood.

Question 34

Magnetic field lines never cross each other but instead push apart from each other.

Question 35

The earth's geographic North Pole has south magnetic polarity and the geographic South Pole has north magnetic polarity.

Question 36

The entire group of magnetic field lines, which can be considered flowing outward from the north pole of a magnet, is called electronic flux.

Question 37

One maxwell unit equals one magnetic field line.

Question 38

The weber is a larger unit of magnetic flux and equals 1 x 10⁸ lines or maxwells.

Question 39

The microweber is smaller than the maxwell unit.

Question 40

The SI units are preferred for science and engineering, but the cgs units are still used in many practical applications of magnetism.

Question 41

In the cgs system, the gauss is one line per square centimeter.

Question 42

In SI, one weber per square meter is called a tesla.

Question 43

Flux density includes total area, whereas flux is for a specified unit area.