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Rad100 > Chpt 5 Part 2 > Flashcards

Chpt 5 Part 2 Flashcards

1
Q

When and who discovered magnetite

A

1000 B.C., shepherds and dairy farmers of village of magnesia (western turkey)

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2
Q

what is a magnetic oxide of iron?

A

magnetite

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3
Q

example of a lodestone or “leading stone”

A

magnetite

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4
Q

What is a naturally occurring magnet and was used as a compass by ancient people

A

magnetite

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5
Q

Any _________ in motion creates a magnetic field

A

charged particle

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6
Q

the magnetic field of a charged particle is _____ to the motion of that object

A

perpendicular

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7
Q

if the particles motion is a closed loop, the magnetic field lines will be perpendicular to the _________

A

plane of motion

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8
Q

Electrons rotate on an _____

A

axis

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9
Q

(T/F) Spinning electron charge is the basis for CT

A

False
MRI

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10
Q

What creates a property called spin?

A

electrons rotating

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11
Q

_____ creates a magnetic field which is neutralized if an ____________ exists in any shell

A

spin
electron pair

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12
Q

Atoms having an odd number of what in any shell exhibits a small magnetic field?

A

electrons

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13
Q

the lines of a magnetic field are always what?

A

closed loops

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14
Q

(T/F) Magnetic fields are called bipolar or dipolar since they always have a north and south pole

A

True

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15
Q

A small magnet created by the electron spin is called what?

A

Magnetic dipole

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16
Q

An accumulation of many dipoles aligned creates what?

A

magnetic domain

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17
Q

one domain = ? atoms

A

10^15

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18
Q

Usually, magnetic domains are ________ distributed

A

randomly

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19
Q

What causes the magnetic domains to align in an object, causing it to act like a magnet?

A

external magnetic field

20
Q

Ferrous materials have ______ domains but in _________ directions

A

many
different

21
Q

When a magnetic comes in close proximity to a ferrous material what happens?

A

it lines up the domains and makes it magnetic

22
Q

When a magnetic comes in close proximity to a non-ferrous material what happens?

A

nothing happens (no domains to align)

23
Q

the magnetic dipoles in a bar magnet generate what?

A

imaginary lines of a magnetic field

24
Q

Lines of flux flow what way outside a magnetic, and what way inside the magnet

A

Outside: N to S
Inside: S to N

25
Q

(T/F) the stronger the magnetic field, the lesser the number of flux lines and the farther away these lines of flux (greater the flux density)

A

False
greater number of flux
closer together

26
Q

Flux lines do what to each other when they are going in the same direction, the opposite direction?

A

same = repel
opposite = attract

27
Q

why does Earth have a magnetic field?

A

has naturally occurring ores (iron) at its core

28
Q

How are magnets classified?

A

according to the origin of the magnetic property

29
Q

Three principal types of magnets:

A
  1. naturally occurring
  2. artificially induced permanent magnets
  3. electromagnets
30
Q

Examples of naturally occurring magnets

A

magnetite/lodestone (iron oxide)

31
Q

What is a coil or wire wrapped around an iron core that intensifies the magnetic fields?

A

electromagnets (temporary magnets)

32
Q

(T/F) Electromagnets are only magnets when the current is flowing

A

True

33
Q

The ease in which a magnet can be magnetized

A

magnetic permeability

34
Q

The ability of a material to stay magnetized

A

retentivity

35
Q

magnetic permeability and retentivity have what type of relationship?

A

inversely proportional

36
Q

Example of ferromagnetic materials

A

iron, nickel, cobalt, alnico, ceramics

37
Q

Examples of paramagnetic materials

A

platinum, aluminum, gadolinium

38
Q

Examples of diamagnetic materials

A

beryllium, bismuth, lead, copper, H20

39
Q

Examples of non-magnetic materials

A

glass, plastic, rubber, wood

40
Q

3 Laws of magnetism

A
  1. repulsion / attraction
  2. ISL
  3. Dipoles: magnetic poles
41
Q

the stronger the magnetic field the ___ lines of flux

A

more

42
Q

The formula for magnetic flux

A

field strength divided by area

43
Q

Units used to measure magnetic flux

A

Weber (wb)

44
Q

1 Wb = ? lines of flux

A

10^8

45
Q

Unit for magnetic flux density

A

Tesla T
Gauss G (British unit)

46
Q

1 Tesla = ? Gauss

A

10,000

47
Q

1 Tesla = ? Wb/m^2

A

1

Rad100 (10 decks)

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