Brainscape's Knowledge GenomeTM

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


See full index

Yr 10-11 Physics > Unit 4 > Flashcards

Unit 4 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Physics flashcards Physics 101 flashcards
1
Q

what do opposite poles do

A

attract

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

what to do similar poles do

A

repel

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

what direction do magnetic field lines always point

A

north to south

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

in attraction, how do the field lines point

A

they point north to south and flow between the 2 points

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

in repulsion, what is the nature of the field lines

A

they point in opposite directions and bend away from each other

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

how is the strength of the magnetic field seen

A

the density of the field lines

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

what happens when permanent magnets attract a magnetic materia

A

a magnetic field is induced in the material

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

what does hard magnetic materials mean

A

they are hard to magnetise and also hard to demagnetise

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

what does soft magnetic materials mean

A

they are easy to magnetise and demagnetise

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

what is an electromagnet

A

when a coil of wire carries current and a magnetic field is induced

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

what are properties of permanent magnets

A

constant magnetic field
cannot be switched on and off
north and south poles cannot be switched
made with hard magnetic materials

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

what are properties of electromagnets

A

variable strength magnet field
can be switched on and off quickly
north and south poles can be changed by changed the direction of current flow
made from soft magnetic materials

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

what are the charge carriers in electrical devices

A

electrons

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

why are conductors able to conduct

A

there electrons are free to move around

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

why are insulators unable to conduct

A

there are no free electrons to move

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

what is a charge

A

an electric charge that can be positive or negative

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

what do unlike charges and like charges do

A

unlike charges attract
like charges repel

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

what happens if there is an equal number of positive and negative charges

A

it is neutral

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

what happens when an object loses electrons

A

it becomes positively charged

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

what happens when an object gains electrons

A

it becomes negatively charged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the symbol for electrical charge and how is it measured

A

symbol is Q
measured in coulombs(C)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is static electricity

A

occurs when friction between 2 insulators causes electrons to be transferred from one surface to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what are electrical fields

A

when 2 charged particles approach each other, they experience a force
the space in which the electric charge experiences a force is called the electric field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is current

A

the measure of the flow of charge
also known as rate of flow of charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

how can current be increased

A

current flow can be increased by:
making each charged particle move faster
increase the number of charged particles
increased the amount of charge each particle carries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

formula for current

A

I = Q/T
current = charge/time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is used to measure current

A

an ammeter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what is conventional current

A

electrons are repelled from the negative terminal of the battery and attracted to the positive terminal
conventional current is the opposite(positive to negative)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what are alternating currents(AC)

A

when the electrons continously change direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what are direct currents(DC)

A

electrons flow in one direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what is electromotive force

A

the phenomena that enables charge to flow around the whole circuit
determined by the battery voltage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what is electromotive force measured in

A

volts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what is potential difference

A

the energy needed per charge to flow between two points in a circuit
work done per unit charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what is potential difference measured with

A

measured with a voltmeter and always placed parallel across a component

35
Q

formula for potential difference and electromotive force

A

V = W/Q
v = voltage
w = energy
q = charge

36
Q

what is resistance

A

the measure of how much opposition there is to the flow of current
measured in ohms

37
Q

what is the formula for resistance

A

R = V/I
r = resistance
v = potential difference
i = current

38
Q

how is the length of the wire related to resistance

A

resistance is directly proportional to the length of the wire

39
Q

how is the thickness of the wire related to resistance

A

it is inversely proportionate
thicker the wire, smaller the resistance

40
Q

what is ohms law

A

electric current is directly proportionate to voltage and inversely proportionate to resistance

41
Q

how can electrical power be calculated

A

P = IV
p = power
i = current
v = potential difference

42
Q

what is a diode

A

only allows current to flow in one direction
requires a small amount of power to activate
non ohmic device

43
Q

what is a light emitting diode(LED)

A

regular diode that lights up when current flows through

44
Q

what is a series circuit

A

the current flows in one loop and voltage is shared throughout. if there are multiple lamps, they will all be dimmer

45
Q

what is a parallel circuit

A

there is more than one loop of current
voltage is the same for all loops

46
Q

advantages of parallel circuits

A

the potential difference across each lamp will be equal to the e.m.f. means every lamp will be brighter
each loop can be turned off separately

47
Q

featurs of series circuits

A

the current will be the same at all points
the potential difference across all resistors is shared
sum of the pd = battery power

48
Q

how to find total resistance in series circuits

A

by adding resistance of all the components up

49
Q

features of parallel circuits

A

the current flowing into a junction is equal to the sum of currents flowing out of a junction
each resistor experiences the same p.d as the power supply

50
Q

how to find total resistance in parallel circuits

A

1/total resistance = 1/resistance of component 1 + 1/resistance of component 2

51
Q

what is Faradays law

A

a wire close to a changing magnetic field will experience an induced electromotive force

52
Q

how can EMF be induced

A

moving a magnet so that its field lines are cut by the wire
moving a wire across a magnetic field

53
Q

what is flemings right hand rule

A

thumb is direction of motion of the wire
first finger is direction of magnetic field
second finger is direction of the current

54
Q

what is Lenz’s law

A

the direction of the induced emf opposes the charge that creates it

55
Q

how can the strength of the induced emf be increased

A

increasing the force or speed at which the wire or hte magnet is moved
increasing the strength of the magnet

56
Q

what happens when the wire moves parallel to the magnetic field

A

an emf is not induced

57
Q

how can the induced emf be decreased

A

decreasing the number of turns in the wire

58
Q

how do AC generators work

A

a rectangular coil of wire continously rotates within a magnetic field and generates an induced emf
the slip rings allow the direction of the induced emf to alternate and cause an ac currect

59
Q

what is the purpose of carbon brushes in AC generator

A

make an electrical connection between the rotating coil and circuit

60
Q

what will the voltage output look like in an AC generator

A

the voltage output will have peaks and troughs as the magnet turns from being parallel to perpendicular

61
Q

what magnetic field does a direct current create

A

it creates a constant magnetic field

62
Q

what magnetic field does an alternating current create

A

an alternating magnetic field

63
Q

what is the magnetic field around a current carrying wire

A

circular

64
Q

whats a solenoid

A

when wires are arranged in a coil, the resulting magnet is the same is that of a bar magnet

65
Q

how can the magnetic field of a solenoid be made stronger

A

increase the current through the solenoid
increase the number of turn in the wire

66
Q

what happens when the solenoid is supplied with an alternating current

A

changes the direction of the magnetic field every half cycle

67
Q

what happens when a current carrying wire is placed within a magnetic field

A

the wire experiences a force and can move

68
Q

how can the size of the force be increases when a current carrying wire is placed in a magnetic field

A

increase the current in the wire
increase the number of individual wires
increase the strength of magnetic field
increase the length of the wire

69
Q

what is the right hand rule used for

A

used to find emf induction

70
Q

what is left hand rule used for

A

used for DC motors

71
Q

what is the difference between AC and DC motors

A

DC motors have a cell that supply it power
AC motors get their current through an induced emf

72
Q

how can DC motors spin quicker

A

increase the strength of the magnetic field
increase the number of turns of wire in the coil
increase the current to the coil from the power supply

73
Q

what are transformers

A

device that can increase or decrease the size of an alternating electromotive force

74
Q

what do step up transformers do

A

increase the voltage

75
Q

what do step down transformers do

A

decrease the voltage

76
Q

what do transformers consist of

A

a primary coil- alternating current supplied through her
soft iron core-allows transition of magnetic flux to a secondary coil
a secondary coil-the output of the transformer and will have more or less coils

77
Q

formula for transformers

A

Vp/Vs = Np/Ns
Vp-voltage applied to primary coil
Np-number of turns in the coil
Vs-voltage applied to secondary coil
Ns- number of turns

78
Q

how many turns does the secondary coil have in a step up

A

the secondary coil has more turns than the primary coil

79
Q

how many turns does the secondary coil have in a step down transformer

A

has fewer turns than the primary coil

80
Q

what current do transformers require

A

they require alternating currents

81
Q

what is formula for 100% efficiency in a transformer

A

IpVp = IsVs

82
Q

how can the efficiency of a transformer increase

A

using low resistance coils to reduce power wasted
using a laminated core which consists of layers of iron separated by layers of insulation

83
Q

how can power loss in a wire be calculated

A

P=1^2R

Yr 10-11 Physics (7 decks)

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