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Magnetism > Magnetism Notes > Flashcards

Magnetism Notes Flashcards

1
Q

What materials do magnets attract?

A

Iron, nickel, cobalt and few minerals/alloys

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2
Q

Where is the force of a magnet strongest?

A

At the poles

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3
Q

How was the first compass made?

A

using magnetite on a piece of floating wood in a dish of water

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4
Q

What is the North pole of the compass actually referring to?

A

magnetic south pole of the earth

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5
Q

What are the three basic types of magnets?

A
  • Natural
  • Artificial
  • Electromagnets
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6
Q

Example of Natural magnet?

A

Lodestone (known as magnetite)

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7
Q

What is Lodestone?

A

A natural magnet that is an oxide of iron (Fe3O4) and is still mined today

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8
Q

example of a permanent magnet?

A

Lodestone

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9
Q

What do artificial magnets not depend on?

A

an electrical current to maintain the magnetic field

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10
Q

difference between artificial and electromagnetic magnets?

A

Electromagnets magnetism depends on current flow where artificial does not

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11
Q

Ferromagnetic?

A

metals that are easily magnetized (iron, nickel, cobalt)

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12
Q

Paramagnetic?

A

metals that are not as easily magnetized (platinum, titanium, chromium)

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13
Q

Diamagnetic?

A

metals or non-metal material that can not be magnetized

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14
Q

One of the best alloys used for permanent magnets?

A

Alnico 5

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15
Q

What is Alnico 5 made of?

A

Aluminum, cobalt, nickel, copper, iron

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16
Q

What is magnetism caused by?

A

Static electrical charges (electrostatic lines of force)

17
Q

What direction do flux lines flow?

A

They exit north and enter south

18
Q

What do flux lines always do?

A

they always form a complete loop and never cross each other

19
Q

How do flux lines pass through all materials?

A

Because there is no insulator

20
Q

What is the property that opposes the setting up of flux lines?

A

reluctance

21
Q

What is used to protect a delicate instrument?

A

a magnetic screen

22
Q

What is a magnetic screen made of?

A

soft iron material due to low reluctance

23
Q

What does a magnetic screen do to flux lines?

A

causes them to bend away from the instrument

24
Q

What determines the amount of magnetic force?

A

the flux density or concentration

25
Q

The greater concentration of flux lines?

A

the stronger the magnetic field

26
Q

Flux lines facing the same direction __________ each other?

A

attract

27
Q

Flux lines facing opposite direction ________ each-other?

A

repel

28
Q

What happens when a magnet achieves max flux density?

A

It is said to be saturated

29
Q

Soft iron (low carbon)?

A

easily magnetized but does not stay magnetized

30
Q

Hard iron (high carbon)?

A

harder to magnetize but will remain magnetized (permanent magnet)

31
Q

what are the atoms like in non magnetized metals?

A

disarranged

32
Q

What are atoms like in magnetized metals?

A

arranged in an orderly fashion (called a domain)

33
Q

How to produce artificial magnets?

A
  • Using DC current
  • By stroking with a magnet
  • by tapping the material
34
Q

What is the most effective way to produce artificial magnets?

A

using DC current

35
Q

Common methods of demagnetizing ferromagnetic material?

A
  • by using heat
  • by vibration or tapping
  • by using AC current
36
Q

Most common way to demagnetize ferromagnetic material?

A

By using AC current to change directions from positive to negative at a rate of 60 cycles per second

37
Q

Precautions to observe to avoid damaging magnets?

A
  • don’t expose magnets to heat
  • do not place magnets near fields made by AC
  • do not drop or subject to vibration
  • has a keeper for horseshoe magnets
  • do not store magnets near other magnets
38
Q

What is a keeper for?

A

preserves the strength of a magnet

Magnetism (7 decks)

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