Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Science > Magnetism and Electromagnetism - Physics Paper 2 > Flashcards

Magnetism and Electromagnetism - Physics Paper 2 Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What does a magnet have around it?

A

A magnetic field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a magnetic field?

A

A region where magnets experience a force acting on them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What type of force is a magnetic force?

A

A non-contact force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What can a magnetic field be represented by?

A

A field diagram

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How many poles do magnets have?

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the 2 poles called?

A

North and South

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do the arrows on magnetic field lines point to?

A

from north to south

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What do the direction of magnetic field lines show?

A

The direction of the force the north pole would feel if it was placed in that location

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

The stronger the magnetic field at any point…

A

the closer together the field lines are

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What do like poles do?

A

Repel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What do unlike poles do?

A

Attract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What’s inside a compass?

A

A tiny bar magnet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the 2 types of magnets?

A

Permanent and induced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do permanent magnets do?

A

They produce their own magnetic fields

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are induced magnets?

A

Magnetic materials that turn into magnets when they’re in a magnetic field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens when you take a magnetic field away from an induced magnet?

A

It loses its magnetism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are examples of permanent magnets?

A

Bar magnets and horseshoe magnets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are some examples of magnetic materials?

A

Iron, steel, nickel, cobalt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens when a current flows through a wire?

A

A magnetic field is created around the wire.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the right-hand thumb rule?

A

You use your right hand and point your thumb in the direction of the current, and curl your fingers. The direction of your fingers is the direction of the field

21
Q

The larger the current through the wire, or the closer to the wire you are…

A

the stronger the field is

22
Q

How can you increase the strength of the magnetic field that a wire produces?

A

by wrapping the wire into a coil called a solenoid

23
Q

How can you increase the magnetic field around a solenoid even further?

A

By putting a block of iron in the centre of the coil. The iron core becomes an induced magnet whenever current is flowing . The magnetic field of the core and the coil combine, making a stronger magnet overall.

24
Q

What is a solenoid with an iron core called?

A

An electromagnet

25
Q

Can electromagnets be switched on and off?

A

Yes

26
Q

What is the motor effect?

A

When a current-carrying wire in a magnetic field experiences a force

27
Q

How do you calculate the force on a wire carrying a current at right angles to a magnetic field?

A

force = magnetic flux density × current × length

28
Q

What are the units of magnetic flux density?

A

Tesla (T)

29
Q

What is magnetic flux density?

A

How many field (flux) lines there are in a region. This shows the strength of the magnetic field.

30
Q

If a current is flowing at 90 degrees to a magnetic field, how can you tell which way the force is acting on the conductor due to the motor effect ?

A

Using Fleming’s left-hand rule

31
Q

How do you use Fleming’s left hand rule?

A

Hold your thumb, forefinger and second finger at right angles to each other:

  • the forefinger is lined up with magnetic field lines pointing from north to south
  • the second finger is lined up with the current pointing from positive to negative
  • the thumb shows the direction of the motor effect force on the conductor carrying the current
32
Q

How can the speed of an electric motor be increased?

A
  • By increasing the current

- By increasing the strength of the magnetic field

33
Q

The direction that a motor turns in can be found using Fleming’s left hand rule and can be reversed either by….

A
  • swapping the polarity of the dc supply

- swapping the magnetic poles over

34
Q

What allows loudspeakers to work?

A

The motor effect

35
Q

What is the generator effect?

A

The generator effect is the induction of a potential difference across a conductor which is experiencing a change in an external magnetic field

36
Q

Which ways can the potential difference across the ends of a conductor be induced?

A
  • By moving the electrical conductor in a magnetic field

- By moving or changing a magnetic field relative to the electrical conductor

37
Q

How can induced potential difference be increased?

A
  • Increasing the speed of the movement

- Increasing the strength of the magnetic field

38
Q

What do alternators do?

A

They generate an alternating current

39
Q

What do dynamos do?

A

They generate direct current

40
Q

What can you use an oscilloscope to see?

A

how potential difference generated in the coil changes over time

41
Q

What are microphones basically?

A

Loudspeakers in reverse that generate current from sound waves

42
Q

What are transformers?

A

Devices that can change the potential difference of an electrical supply using the generator effect.

43
Q

What is the structure of transformers?

A

They consist of 2 coils, the primary and secondary, wrapped around an iron core. Iron is used as a core because it magnetises and demagnetises quickly.

44
Q

Why is iron used as the core of transformers?

A

Iron is used as a core because it magnetises and demagnetises quickly.

45
Q

What are the 2 types of transformers?

A

The step down transformer and the step up transformer

46
Q

What happens in step-up transformers?

A

The number of turns on the secondary coil and the size of the pd across it are greater than across the primary coil.

47
Q

What happens in step-down transformers?

A

The number of turns on the secondary coil and the size of the pd across it are smaller than across the primary coil

48
Q

What is the transformer equation?

A

potential difference across primary coil / potential difference across secondary coil = number of turns on primary coil/number of turns n secondary coil

49
Q

potential difference across secondary coil X current in secondary coil =

A

= potential difference across primary coil X current in primary coil

Science (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions