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Physics > 4th - Magnetism And Electromagnetism > Flashcards

4th - Magnetism And Electromagnetism Flashcards

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1
Q

Like charges …

A

Repel

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2
Q

Opposite charges…

A

Attract

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3
Q

Example of a magnetically soft material
Use?

A

Iron
- electromagnets

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4
Q

Example of a magnetically hard material
Use?

A

Steel
- permanent magnets

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5
Q

How does iron become magnetised

A

The presence of a magnetic field, which forces magnetic domains into alignment

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6
Q

Examples of magnetic metals

A

Steel
Iron
Nickel

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7
Q

Examples of non magnetic materials

A

Wood
Aluminium

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8
Q

What happens if a magnetic field is removed

A

Magnetism is lost
- domains go back to random orientation

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9
Q

What does it mean if a material is magnetically soft

A

It loses its magnetism easily if removed from a magnetic field

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10
Q

What does it mean if a material is magnetically hard

A

It’s domains are locked in alignment - doesn’t lose magnetism easily when removed from a magnetic field

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11
Q

How can aligned domains be effectively jumbled

A

Heating or striking the magnets on a hard surface

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12
Q

What do magnetic material feel when they are in a magnetic field

A

Magnetic force

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13
Q

Definition of a magnetic field

A

A region where a magnetic material experiences a force

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14
Q

What does magnetic field line show the direction of

A

Direction of the magnetic force ( from north to south)

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15
Q

Which ways will the arrows be pointing on a magnetic field line

A

North to south

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16
Q

How does the magnetic field lines convey the strength of a field

A

Tightly packed field lines indicate a strong magnetic field

17
Q
  • practical
    Investigate the magnetic field pattern for a permanent bar magnet, and between two bar magnets
    ( using a compass)
A
  • bar magnet in centre of paper
  • compass at edge of North Pole
  • mark where North Pole of compass is pointing
  • move compass so south end lined up w dot that u just plotted
  • mark where North Pole of compass is pointing
  • continue until you end at South Pole
  • repeat for several field lines
18
Q
  • practical
    Investigate the magnetic field pattern for a permanent bar magnet, and between two bar magnets
    (Using iron filings)
A
  • paper over bar magnet
  • iron filings sprinkled over paper ( they become induced magnets )
  • tap paper gently with your finger
  • iron filings will line up with field lines
19
Q

How to create a uniform field

A
  • two bar magnets
  • north and South Poles facing
  • close, but not too close that they move together
20
Q

What does a uniform field look like

A

Evenly spaced
Parallel
Uniform, straight

21
Q

Do magnetic field lines ever intersect

A

No

22
Q

What is a neutral point between two repelling magnets

A

The resultant field is zero

23
Q

What is Flemings left hand rule

A

First finger = magnetic Field
seCond finger = Current
Thumb = force

24
Q

What is a solenoid

A

A coiled wire

25
Q

What increases the strength of an electromagnet

A
  • Number of turns of coil
  • increase current
  • add an iron centre
26
Q

Use of an electromagnet

A

School bells, fire alarms

27
Q

How is an electromagnet different to a normal magnet

A
  • can turn off an EM - cant turn off a normal one
  • can increase strength of an EM - can’t in normal one
28
Q

What is a motor effect

A

The effect where a force is exerted on a wire carrying a current in a magnetic field

29
Q

How do you make a motor stronger

A
  • increase voltage/ current
  • move magnet closer to wire
  • use shorter magnet
30
Q

How can you change the direction of the motor

A
  • reverse current
  • reverse poles of the magnet
31
Q

What current does a motor use

A

Alternating current

32
Q

Definition of scalar

A

Magnitude only (size)

33
Q

Definition of vector

A

Magnitude and direction

34
Q

What current does a loudspeaker use

A

AC current
- current goes back and forth (constantly changing direction)
- pushes the solenoid back and forth which also pushes the cone - amplifying sound

35
Q

Explain Right hand grip rule

A

Holding pen (wire) in RH with thumb pointing in direction of current. Fingers show the direction of the magnetic field

36
Q

What does a x mean when figuring out the direction of current

A

Current is going into page

37
Q

What does a dot mean when figuring out direction of current

A

Current is going out of page

Physics (7 decks)

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