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Physics GCSE > Magnetism (11) > Flashcards

Magnetism (11) Flashcards

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1
Q

Magnets produce _____________ fields

A

Magnetic

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2
Q

A magnetic field is a region where magnetic materials experience a __________

A

Force

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3
Q

Magnetic field lines are used to show the ________ and ____________ of magnetic fields

A

Size Direction

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4
Q

Magnetic field lines always point from _________ to __________

A

North South

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5
Q

Placing the north and south poles of 2 permanent bar magnets near each other creates a uniform __________ between the 2 magnets

A

Field

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6
Q

Like poles repel each other and opposite poles __________

A

Attract

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7
Q

When a magnet is brought near a magnetic material then the material acts as a __________. This magnetism has been ___________ by the original magnet.

A

Magnet Induced

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8
Q

The closer the magnet and the magnetic material get, the ___________ the induced magnetism will be

A

Stronger

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9
Q

Far from the magnet - __________ induced magnetism

A

Little magnetism induced

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10
Q

A current-carrying wire creates a _______________ field

A

Magnetic

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11
Q

An electric current in a material produces a _____________ field around it

A

Magnetic

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12
Q

The larger the electric current, the ___________ the magnetic field

A

Stronger

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13
Q

The direction of the magnetic field depends on the direction of the ___________

A

Current

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14
Q

What is the magnetic field around a straight wire

A

Concentric circles with the wire in the centre … right hand grip rule: Hold your right hand in such a way that your thumb points in the direction of the current, the curl of your finger will points in the direction of the magnetic field.

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15
Q

What is the magnetic field around a flat circular coil

A

The magnetic field is similar to that of a bar magnet. Concentric ellipses of magnetic field lines around the coil

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16
Q

What is the magnetic field inside a current-carrying solenoid like

A

Strong and uniform

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17
Q

What is the magnetic field outside a current-carrying solenoid like

A

Just like the one around a bar magnet

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18
Q

The ends of a ____________ act like the north and south pole of a bar magnet. This type of magnet is called an ________________________

A

Solenoid Electromagnet

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19
Q

When is a magnetic material considered soft

A

If it loses its induced magnetism quickly

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20
Q

When is a magnetic material considered hard

A

If it keeps its induced magnetism permanently

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21
Q

How can you increase the strength of the magnetic field around a solenoid

A

By adding a magnetically ‘soft’ iron core though the middle of the core`

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22
Q

How do 2 magnetic fields cause a current-carrying wire to move

A

When a current-carrying wire is put between magnetic fields, the 2 magnetic fields affect each other. The result is a force on the wire causing the wire to move.

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23
Q

Why do 2 magnetic fields cause a current-carrying wire to move

A

Because charge particles moving through a magnetic field will experience a force, as long as they’re not moving parallel to the lines

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24
Q

To experience the full force, the wire has to be _____ to the magnetic field

A

90°

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25
Q

If the wire runs __________ the magnetic field, it won’t experience any force at all. At angles between, it’ll feel …

A

Along

Some force

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26
Q

The force always acts in the _________ direction relative to the magnetic field of the magnets

A

Same

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27
Q

What is a good way of showing the direction of the force

A

To apply a current to a set of rails inside a horseshoe magnet. A bar is placed on the rails, which completes the circuit. This generates a force which rolls the bar along the rails.

28
Q

The magnitude (strength) of the force ____________ with the strength of the magnetic field

A

Increases

29
Q

The force _____________ with the amount of current passing through the conductor

A

Increases

30
Q

Reversing which 2 things can reverse the direction of the force

A

The current or the magnetic field

31
Q

Fleming’s left hand rule: What does the thumb represent

A

Force/Motion

32
Q

Fleming’s left hand rule: What does the first finger represent

A

Magnetic field

33
Q

Fleming’s left hand rule: What does the second finger represent

A

Current

34
Q

4 factors which speed up an electric motor:

A

More current

More turns on the coil

Stronger magnetic field

A soft iron core in the coil

35
Q

What does the split-ring commuter do

A

It swaps the contacts every half turn to keep the motor rotating in the same direction

36
Q

How can the direction of an electric motor be reversed

A

By swapping the polarity of the d.c. supply OR by swapping the magnetic poles over

37
Q

How can you work out which way the coil will turn

A

By using fleming’s left hand rule

38
Q

Uses of an electric motor

A

Electric bell

Crane

39
Q

What is electromagnetic induction

A

The creation of voltage in a wire which is experiencing a change in magnetic field

40
Q

What is the dynamo effect

A

Using electromagnetic induction to transform kinetic energy into electrical energy.

41
Q

What are the 2 different situations where you get electromagnetic induction

A

An electric conductor moves through a magnetic field.

The magnetic field through an electrical conductor changes

42
Q

How can you test for electromagnetic induction

A

By connecting an ammeter to a conductor and moving the conductor througha magnetic field. The ammeter will show the the magnitude and direction of the induced current.

43
Q

Dynamo effect: If the direction of movement is reversed, then the induced voltage/current will be _____________

A

Reversed

44
Q

Dynamo effect: To get a bigger voltage, what 3 things can you increase

A

The strength of the magnet

The number of turns on the coil

The speed of movement

45
Q

In an electric motor - you’ve got a current in the wire and a magnetic field which causes ______________.

In a generator it works the opposite way round - you’ve got a magnetic field and movement which induces a _____________.

A

Movement

Current

46
Q

Generators rotate a coil in a ____________ field. Their construction is pretty much like a ________.

A

Magnetic

Motor

47
Q

A.C. Generators: As the coil spins, a _________ is induced in the coil. This current changes ____________ every half turn. Instead of a split-ring commutator, A.C generators have ______ _______ and ____________ so the contacts don’t ________ every half turn. This means they produce a.c. voltage, shown by ______ displays

A

Current

Direction

Slip rings

Brushes

Swap

CRO

48
Q

Power stations use A.C generators to produce _______________

A

Electricity

49
Q

Transformers only work with an _________________ current

A

Alternating

50
Q

Transformers change the size of the ____________ of an alternating current

A

Voltage

51
Q

All transformers have 2 coils, the primary and the secondary, joined with an _______ core

A

Iron

52
Q

When an alternating voltage is applied across the primary coil, the magnetically soft (iron) core ______________ and ____________________ quickly. This induces an alternating _____________ in the ______________coil

A

Magnetises

Demagnetises

Voltage

Secondary

53
Q

What does a step-up transformer do? They have more turns on the _____________ coil than the _____________ coil.

A

Step the voltage up.

Secondary.

Primary.

54
Q

What does a step-down transformer do? They have more turns on the _____________ coil than the _____________ coil.

A

Step the voltage down.

Primary.

Secondary.

55
Q

The transformer equation:

A
56
Q

What does p stand for in the transformer equation:

A

Primary

57
Q

What does s stand for in the transformer equation:

A

Secondary

58
Q

What does V stand for in the transformer equation:

A

Voltage

59
Q

What does N stand for in the transformer equation:

A

Number of turns

60
Q

Transformers are nearly 100% ______________

A

Efficient

61
Q

What is the word formula for power supplied

A

Power = Voltage x Current

62
Q

You can rewrite input power = output power as:

A

Vp x Ip = Vs x Is

(Primary voltage x Primary current = Secondary voltage x secondary current)

63
Q

Transformers make transmitting mains electricity more ______________

A

Efficient

64
Q

Step-up and step-down transformers are used when transmitting _________________ across the country

A

Electricity

65
Q

The _____________ produced by power stations is too low to be transmitted efficiently. Power = VI, so the lower the voltage the __________ the current. A step-_____ transformer is used to boost the voltage before it is transmitted. Step-_______ transformers are used at the end of the journey to ________the voltage so it’s more useful and safer to use.

A

Voltage

Higher

Step-up

Step-down

Reduce

Physics GCSE (22 decks)

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