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Test #2 Physics > Ch.6 Magnetism > Flashcards

Ch.6 Magnetism Flashcards

1
Q

What is magnetism?

A

Fundamental property of some forms of matter

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2
Q

What does magnetism have the ability to do?

A

Attract iron

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3
Q

Any charged particle in motion creates what?

A

A magnetic field

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4
Q

How is the magnetic field positioned in relation to the charged particles motion?

A

Perpendicular

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5
Q

What parts of the atom exhibit a net magnetic charge?

A

The proton and electron

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6
Q

Which part of the atom has no net magnetic charge?

A

The neutron

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7
Q

What properties does a particle have to have in order to exhibit a net magnetic charge?

A

They need to have movement and have a positive or negative charge

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8
Q

Why do neutrons have no magnetic field?

A

Because of their neutral charge

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9
Q

Describe spin.

A

An exotic movement that neutrons, protons, and electrons all share

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10
Q

Why do protons and electrons develop north and south poles?

A

Because of their positive and negative charge

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11
Q

What is a magnetic moment?

A
  • One electron with its rotation counterclockwise and their north poles pointing upwards
  • One electron with its rotation clockwise and their north pole pointing downwards
  • opposite directions canceling each other out
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12
Q

When an electron orbit is filled with its paired electrons the 2 magnetic moments must be opposite. They cancel each other out so that there is no what?

A

No net magnetic field for the orbit

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13
Q

Which elements on the periodic table have no magnetic field? Why?

A
  • Even numbered Z#’s or atomic numbers

- because they have an unpaired electron forming a magnetic dipole

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14
Q

Which elements on the periodic table have net magnetic fields? Why?

A
  • Odd Z#’s or atomic numbers

- because they contain an unpaired electron

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15
Q

Where will most magnetic moments not be cancelled out?

A

In the outer shell

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16
Q

What is a magnetic domain?

A

An entire atom with a magnetic field.

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17
Q

If domains point in different directions do they have a magnetic field? Why or why not?

A

No because the random alignment of the domains tend to cancel one another out

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18
Q

Describe magnetic domains in ferrimagnetic materials.

A

They are regions in which the atoms line up their magnetic dipoles in the same direction

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19
Q

What happens to the magnetic domains in ferromagnetic materials when it becomes influenced by an external magnetic field?

A

The regional domains all line up uniformly with the external magnetic field.

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20
Q

What are types of ferromagnetic materials?

A

Iron and nickel… Alloy metals

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21
Q

What else can induce a magnetic field?

A

Spinning electric charges.

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22
Q

What are the 3 types of magnets?

A
  • Natural
  • Permanent or Artificial
  • Electromagnets
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23
Q

What are different types of natural magnets? Strong or weak?

A
  • Ferromagnetic rocks, lodestones

- Weak natural magnets

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24
Q

What are some types of permanent or artificial magnets?

A
  • Conventional magnets
  • Ferromagnetic metals in various sizes such as bars, horseshoes, discs
  • To magnetize a ferromagnetic object a strong permanent magnet may be stroked along side it
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25
Q

A solenoid (coil of wire) with electrical current flowing through it wrapped around an iron bar is a what?

A

Electromagnet

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26
Q

The ease with which a material can be penetrated by an external magnetic field, and thus magnetized, is called its what?

A

Permeability

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27
Q

What can a permeable material be thought of?

A

Magnetically soft

28
Q

The ability of the material to retain or hold on to its magnetism over time is called its what?

A

Retentivity

29
Q

Tapping on or jolting a permanent magnet outside of an external magnetic field shakes the magnetic domains back into random configurations this causes the object to what?

A

Lose its electric force therefore losing its retentivity

30
Q

Magnets always remain what?

A

Dipolar or bipolar

31
Q

What do ideal magnets have?

A
  • High permeability

- High retentivity

32
Q

T/F: Most magnets tend to be high in either permeability or retentivity and low in the other.

A

True

33
Q

What does dipolar and bipolar mean?

A

Retaining two poles, north and south

34
Q

If a magnet is broken into two smaller magnets, each with develop its own what?

A

North and south poles

35
Q

What is a solenoid?

A

A coil of wire

36
Q

By passing electricity through a coil of wire or solenoid a strong what is created?

A

Electromagnet with north and south poles

37
Q

How can you farther strengthen and multiply an electromagnet?

A

By inserting an iron bar into the coil

38
Q

What are the lines of force of a magnetic field?

A

Flows outward from the North Pole then circulates down and around and flows into the South Pole

39
Q

What type of magnetic dipole does a H atom have?

A

They have a strong magnetic dipole because of the single unpaired electron it has

40
Q

What type of magnetic dipole does a H2 atom have?

A

Has no magnetic dipole because its two electrons cancel each other out.

41
Q

In an MRI the energy given up is the same that is taken in meaning the energy is a what?

A

Giver and receiver

42
Q

What are conventional magnets made of?

A

A mixture of Iron, nickel, cobalt, and other ferromagnetic materials

43
Q

Which law states that the strength or intensity of the magnetic field is proportional to the product of the pole strengths, and inversely proportional to the square of the distance between them?

A

Gauss Law

44
Q

What is the equation to gauss’ law?

A

F= k P1*P2/ D^2

45
Q

What do the letters in Gauss law stand for? F= k P1*P2/ D^2

A

F= force
K= constant of 1
P1 and P2= the strength of the pole from each magnet
D^2= distance between poles

46
Q

What is the unit with which pole strength is measured?

A

G, gauss

47
Q

A Tesla is equal to how many Gauss?

A

10,000

48
Q

A typical MRI generates how many Tesla?

A

1.0-1.5

Today it is between 2-3T which reduces overall scan time

49
Q

The study of electrical charges a rest, or static electricity, as distinguished from regularly moving electrical current is known as?

A

Electrostatics

50
Q

An object becomes ____ any time it develops either an excess electron or a deficiency of electrons.

A

Electrified

51
Q

Discharges of electrostatic charges are in the form of what?

A

From small sparks to lightening

52
Q

What acts as an infinite reservoir for charges? By grounding these structures, any static electricity built up on them can be dissipated.

A

The ground of the earth

53
Q

Electric charge comes in what discrete units?

A

Negative or positive associated with electrons and protons

54
Q

What is the difference between electron and protons movement?

A

Electrons move from one atom to another while protons are fixed.

55
Q

Electrostatics deals with mostly what charge?

A

Negative/ Electrons

56
Q

What is the charge in Coulombs of an electron?

A

1.6x10^-19 C

57
Q

How many electron charges = Coulomb?

A

6.3x10^18 electron charges = 1 Coulomb

58
Q

The following are the laws of what?

  1. Like charges repel while opposite charges attract
  2. In solid objects electric charges exist only on the surface of the object.
  3. In solid objects the charge will concentrate at the greatest curvature of the surface
  4. The force of electric charge follows Coulomb’s law
A

The 4 laws of electrostatics

59
Q

Objects can become electrified in what 3 ways?

A
  1. Friction
  2. Contact
  3. Induction
60
Q

How do electrons become electrified by friction?

A

When electrons are rubbed off of materials with loosely bound electrons onto other materials

61
Q

How do electrons become electrified by contact?

A

Whenever a potential difference exists between two objects that touch each other

62
Q

How do electrons become electrified by induction?

A

Occurs when a charged object induces charge in another object nearby without directly touching it.

63
Q

A neutral object becomes electrically ____ when a charged object is brought near and attracts opposite charges in induction.

A

Polarized

64
Q

Materials that are only slightly attracted to strong magnets are_____? What are two examples of this material?

A

Paramagnetic, oxygen and sodium

65
Q

Substances that are repelled away from magnets are called ______. What are two examples of this material?

A

Diamagnetic, glass and water

Test #2 Physics (4 decks)

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