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Physics > Magnetism Test > Flashcards

Magnetism Test Flashcards

1
Q

Magnets have two poles…

A

North (or north seeking) and South (or south seeking)

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2
Q

There are two types of magnets…

A

Permanent and Induced

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3
Q

Permanent magnets…

A

Produce their own magnetic field

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4
Q

Induced magnets…

A

Are magnetic materials that turn into a magnet when placed in a magnetic field

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5
Q

The force between permanent and induced magnets are…

A

Always attractive

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6
Q

When the magnetic field is taken away, induced magnets…

A

Lose most or all of their magnetism

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7
Q

When a current is flowed through a wire…

A

A magnetic field is created around the wire

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8
Q

The magnetic field of a wire is made up of…

A

Concentric circles perpendicular to the wire that is carrying the current

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9
Q

Changing the direction of the current…

A

Changes the direction of the magnetic field

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10
Q

The Right-Hand Thumb Rule is…

A

Using the right hand to find the direction of the field by:

  • Pointing the thumb in the direction of the current
  • Curling the other fingers into the palm of the hand
  • Finding the direction of the field by following the root of the fingers to the tips
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11
Q

The strength of the magnetic field produced by a wire changes…

A

With the current and distance from the wire. More current and less distance = stronger field, less current and more distance = weaker field

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12
Q

A solenoid…

A

Is a coil of wire

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13
Q

The strength of the field of the wire can be strengthened even further by…

A

Wrapping the wire into a coil

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14
Q

The strength of a solenoid is greater than that of a straight wire because…

A

Each loop of the wire line-up with each other resulting in lots of field lines pointing in the same direction which are very close together

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15
Q

The magnetic field inside a solenoid is…

A

Strong and uniform (same strength and direction at every point in that region)

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16
Q

The magnetic field outside a solenoid is…

A

Just like that of a typical bar magnet

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17
Q

The field strength of a solenoid can be strengthened by…

A

Placing an iron core in the centre of the coil which makes the iron core an induced magnet

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18
Q

When a current is no longer present in a wire…

A

The magnetic field disappears

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19
Q

A solenoid with an iron core is…

A

An electromagnet

20
Q

An electromagnet is defined as…

A

A magnet that can be turned on and off with an electric current

21
Q

Electromagnets can be used within circuits as…

A

Switches

22
Q

The motor effect is…

A

When a conductor (e.g current-carrying wire) is put between magnetic poles, the magnetic field around the wire interacts with the magnetic field it has been placed in; causing the magnet and the conductor to exert a force on each other

23
Q

To experience the full-force of a magnetic field…

A

The wire has to be perpendicular to the magnetic field

24
Q

The force of a magnetic field always acts

A

At right angles

25
Q

The magnitude (strength) of the force…

A

Increases with the strength of the magnetic field and the amount of current passing through the conductor

26
Q

The force acting on a conductor in a magnetic field depends on three things…

A

Magnetic flux density, size of current and the length of the conductor that’s in the magnetic field

27
Q

The magnetic flux density is…

A

The amount of field lines there are in a region, showing the strength of the magnetic field

28
Q

Fleming’s Left-hand rule is…

A
  • Using the left hand and pointing the first finger in the direction of the field (First - Field)
  • Point the second finger in the direction of the current (seCond - Current)
  • The thumb will then point in the direction of the force (thuMb - Motion)
29
Q

A current-carrying coil of wire…

A

Rotates in a magnetic field

30
Q

If the coil is on an axle…

A

The forces act one up and one down, causing it to rotate

31
Q

The direction of the motor can be reversed by…

A

Reversing the current or by reversing the field

32
Q

The direction of the coil’s turn can be found with…

A

Fleming’s left-hand rule

33
Q

Electricity is generated by…

A

Using the generator effect

34
Q

The generator effect induces…

A

A potential difference in a conductor and a current if the conductor is a part of a complete circuit

35
Q

You can create the generator effect by…

A

Moving a magnet in a coil of wire or moving a conductor (e.g wire) in a magnetic field

36
Q

If the magnet or conductor is moved in the opposite direction…

A

The potential difference and current will be reversed

37
Q

If the magnet keeps moving backwards and forwards…

A

A potential difference is produced that keeps swapping direction which is called an alternating current

38
Q

The generator effect can be replicated by…

A

Turning a magnet end to end in a coil, or turning a coil inside a magnetic field. This is how generators produce alternating current (ac) or direct current (dc)

39
Q

As the magnet turns…

A

The magnetic field through the coil changes, introducing a potential difference which can make a current flow within the wire

40
Q

Every time the magnet moves through a half turn…

A

The magnetic field of the coil and the potential difference reverses. This causes the current to flow the opposite direction

41
Q

If the magnet is turned in the same direction continuously…

A

The potential difference will keep reversing and a alternating current will be produced

42
Q

The magnetic field created by an induced current…

A

Always acts against the change that made it. Or in other words: it’s trying to return things to the way they were

43
Q

Alternators…

A

Generate alternating current

44
Q

Dynamos…

A

Generate direct current

45
Q

The construction of alternators and dynamos are similar…

A

To the construction motors

46
Q

Alternators use slip rings and brushes…

A

So that the contacts don’t swap every half turn

47
Q

Dynamos use split-ring commutator instead of slip rings because…

A

They swap the connections every half turn to keep the current flowing in the same direction

Physics (6 decks)

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