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Electrical Theory > Magnetism > Flashcards

Magnetism Flashcards

1
Q

Ampere-turn

A

basic unit of measurement for magnetism
number of turns of wire x current flow

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2
Q

Demagnetized

A

removal of magnetism from an object

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3
Q

Electromagnets

A

magnets that rely on electricity to become magnetized

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4
Q

Electron spin patterns

A

pattern or direction in which electrons spin as they orbit the nucleus of an atom

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5
Q

Flux

A

magnetic lines of force

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6
Q

Flux density

A

number of magnetic lines contained in a certain area

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7
Q

Left-hand rule

A

rule used for determining the polarity of an electromagnet when direction of current flow is known (in a conventional flow circuit)

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8
Q

Lines of flux

A

lines of magnetic force

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9
Q

Lodestones

A

natural magnets

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10
Q

Magnetic domains/molecules

A

section within a magnetic material where atoms are aligned to produce a north or south south polarity

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11
Q

Magnetomotive force

A

magnetic force produced by current flowing through a conductor or coil

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12
Q

Permanent magnets

A

magnets that don’t require an external force to maintain their magnetic properties

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13
Q

Permeability

A

measurement of a material’s ability to to conduct magnetic lines of flux; standard is air w/a permeability of 1

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14
Q

Reluctance

A

resistance to magnetism

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15
Q

Residual magnetism

A

amount of magnetism left in an object after magnetizing force has been removed

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16
Q

Saturation

A

maximum amount of magnetic flux a material can hold
when all the molecules of a magnetic material are lined up

17
Q

What is the magnetic polarity of the geographic north

A

south polarity

18
Q

What is the magnetic polarity of the geographic south

A

north polarity

19
Q

Angle of declination

A

angular difference between the geographic pole and the magnetic pole

20
Q

T/F: Energy is required to create a magnetic field but no energy is required to maintain a magnetic field

A

True

21
Q

List the 3 natural magnets

A

Iron (Fe)
Nickle (Ni)
Cobalt (Co)

22
Q

List some ferromagnetic materials

A

Fe
Ni
Co
Mn (Manganese)

23
Q

Ferromagnetic

A

easily magnetized materials

24
Q

List some paramagnetic materials

A

Platinum (Pt)
Titanium (Ti)
Chromium (Cr)

25
Q

Paramagntetic

A

materials that can be magnetized but not as easily as those that are ferromagnetic

26
Q

List some diamagnetic materials

A

Copper (Cu)
Brass
Antimony (Sb)

27
Q

Diamagnetic

A

materials that cannot be magnetized

28
Q

What are the best types of materials to make into magnets and why

A

ferrites because they are insulators

29
Q

T/F flux lines surround the entire magnet

A

true

30
Q

what is the law of electromagnetism

A

when an electric current flows through a conductor, a magnetic field is formed around the conductor

31
Q

what happens to the electromagnetic field once current stops

A

it no longer exists

32
Q

air core magnet

A

EM in which a coil is wrapped around a nonmagnetic material

33
Q

iron core magnet

A

EM in which coil is wrapped around magnetic material

34
Q

which has a stronger magnetic field: air core or iron core

A

iron core

35
Q

coercive force

A

how well a material retains it’s magnetism

36
Q

magnetomotive force formula

A

phi x rel

37
Q

what are ways to demagnetize materials

A

place object in the field of a strong electromagnet that is connected to an AC circuit
strike it
heat it

38
Q

Solenoid

A

when a coil is wrapped around around a material for the purpose of producing an electromagnetic field

39
Q

Magnetic field is directly or indirectly proportional to it’s ampere-turns

A

directly (more ampere-turns means a stronger field)

Electrical Theory (5 decks)

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