Electro Magnetism Flashcards

1
Q

What are the two poles

A

North and South

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2
Q

What do all magnets produce

A

A magnetic field

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3
Q

What is a magnetic field

A

A region where other magnets or magnetic materials experience a force

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4
Q

Is magnetism a contact or non-contact force

A

Non contact

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5
Q

What are the 4 magnetic materials

A
  • Iron
  • Steel
  • Nickel
  • Cobalt
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6
Q

What do you use to show a magnetic field and how do you show it

A
  • Magnetic field lines
  • lines go north to south
  • they show which way a force would act on a North Pole if it was put at that point in the field
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7
Q

What does it mean if the magnetic field lines are closer together

A
  • the stronger the magnetic field
  • (So for when they’re further apart = weaker field)
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8
Q

What is the force between a magnet and a magnetic material like

A

Attractive (always, no matter the pole)

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9
Q

like poles will

A

Repel

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10
Q

Unlike poles will

A

Attract

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11
Q

What can a compass show

A

The direction of Magnetic fields

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12
Q

How do compasses show the direction of the Magentic field

A
  • tiny metals needle in compass
  • it’s North Pole is attracted to the South Pole of any magnet nearby
  • so points in direction of magnetic field
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13
Q

Why do compasses point north

A
  • Earth generates its own magnetic field, which shows that the inside (core) of the Earth must be magnetic
  • the compass need then points north because of this
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14
Q

What are the 2 types of magnets

A
  • permanent
  • induced
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15
Q

What are permanent magnets

A

They produce their own magnetic fields

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16
Q

What are induced magnets

A

Magnetic material that turn into a magnet when they’re put into a magnetic field

17
Q

Describe the force between a permanent and induced magnet

A

Attractive

18
Q

What happen when you take an induced magnet out of a magnetic field

A

It loses most of its magnetism

19
Q

What creates a magnetic field

A
  • when a current flows through a wire, a magnetic field is created around the wire
20
Q

Describe the magnetic field around a wire

A
  • made up of concentric circles perpendicular to the wire
  • with the wire in the centre
21
Q

How do you see the magnetic field around a wire

A
  • place a compass near wire that’s carrying current
  • As you move the compass, it’ll trace the direction of the magnetic field
22
Q

How does changing the direction of current in a wire affect the magnetic field around the wire

A
  • changing direction of current = changes direction of magnetic field
  • use the hand-thumb rule to work out which way it goes
23
Q

What from the wire affects the strength of the magnetic field

A
  • The strength of the magnetic field changes WITH the current and the distance from the wire
  • the larger the current or the closer you are to the wire = the stronger the field is
24
Q

What is a solenoid

A

A coil of wire

25
Q

How do you increase the strength of a magnetic field produced by a wire

A
  • wrapping the wire into a coil called a solenoid
26
Q

Why does wrapping a wire into a solenoid increase the strength of the magnetic field

A
  • the field lines around each loop of wire line up with each other
  • resulting in lots of field lines pointing in the same direction that are very close together
  • and therefore the closer the field lines are = the stronger the field is
27
Q

Describe the magnetic field inside a solenoid

A
  • strong
  • uniform
    —> it has the same strength and direction at every point in that region
28
Q

Describe the magnetic field outside a solenoid

A

Just like that around a bar magnet

29
Q

How can you further increase the field strength of a solenoid even more

A
  • put a block of iron in the centre of the coil
  • the iron core becomes an induced magnet whenever current is flowing
  • (But if you stop the current, the magnetic field disappears)
30
Q

What is a solenoid with an iron core called

A
  • electromagnet
  • (a magnet whose magnetic field can be turned on and off with an electrical current)
31
Q

What happens to a current in a Magnetic field

A
  • it experiences a force
32
Q

Explain the Motor effect

A
  • current carrying wire (conductor) is put between magnetic poles
  • magnetic field around wire interacts with magnetic field it has been placed into
  • causing magnet and conductor to exert a force on each other
  • causing the wire to move
33
Q

How do you make the wire experience the full force of the motor effect

A
  • place it 90’ in a magnetic field
  • if it’s parallel = no force
34
Q

How does the force act in the motor effect

A
  • at right angles to the magnetic field
  • and the direction of the current in the wire
35
Q

As the strength increases, what happens to the magnitude of the force

A

Increases
—> it’ll also increase with the amount of current passing through the conductor

36
Q

What does the force acting on a conductor in a magnetic field depend on

A
  • magnetic flux density
  • size of current through conductor
  • length of conductor that’s in the magnetic field
37
Q

What is the magnetic flux density

A

How many field lines there are in a region
—> shows strength of a magnetic field

38
Q

How do you find the direction which a force is acting during the motor effect

A
  • Fleming’s left hand rule
  • thuMb = Motion
  • First finger - Field
  • seCond finger = Current
39
Q

What happens to a current-carrying coil of wire in a Magnetic field

A

It will rotate