Brainscape's Knowledge GenomeTM

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


See full index

GCSE Physics <3 > Topic 2 – Electricity Fundamentals > Flashcards

Topic 2 – Electricity Fundamentals Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards GCSE Religious Studies - Edexcel Route A flashcards AP® Physics flashcards GCSE Religious Studies - Eduqas Route A flashcards GCSE Geography - AQA flashcards GCSE Religious Studies - Edexcel Route B flashcards GCSE Religious Studies - Eduqas Route B flashcards
1
Q

in a circuit, the electric current flows from _____ to the____

A

negative end of the cell to the positive end

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

in a lamp, electrical energy is transferred to what?

A

to light energy and thermal energy

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

when electrons return to the positive end of the cell, they’re carrying ___ energy than when they left the negative end

A

less

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

whats the conventional current?

A

the oppositely drawn flow of charge (silly stupid thing)

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

what is current

A

the flow of electric charge around a circuit. the unit is aperes

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

in a series circuit, current is ______ all way round

A

the same

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

in a parallel circuit, current _____

A

in each branch ADD UP to the total current leaving the cell

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

the cell has a tranfer of_____ energy which is transfered to ______ energy

A

chemical
electrical

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

a potential difference of 1 volt tells us that:

A

1 joule of energy is transferred for each coulomb of charge that is moving through the circuit

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

placing 2 lamps in a series circuit would make them____

A

dimmer

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

how does voltage work in a series circuit

A

the total potential difference across both lamps is the SAME a the p.d across the cell. (NOT ALWAYS EQUALLY SHARED but split)

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

how does voltage work in a parallel circuit?

A

for component connected in parallel, the potential difference across each component is the same.

(2 lamps in 1 branch counts as series)

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

whats the voltage of 2 cells facing the right way and the wrong way?

A

the voltage cancels out, making 0

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

whats electrical charge measured in?

A

coulombs

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

a current of 1 ampere means what in coulombs

A

1 coulomb of charge flowing per second

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

the size of the elctric current is the rate of______

A

flow of an electrical charge

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

whats the equations for charge?

A

charge (Q) = current (I) x (t) time

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

whats the equation for energy transferred?

A

E = Q x V

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

what does resistance tell you

A

the potential difference required to drive a current through a component

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

whats the equation for resistance ?

A

R = V/I

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

current through a resistor is______ to potential difference

A

directly proportional

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

resistance is _____ . It _______ if we change the current

A

constant

does not change

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

resistance will only stay constant if:

A

temperature is constant

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

what do we call resistors which have a constant resistance?

A

ohmic conductors

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

the current through a. filament lamp is _____ to potential difference

A

not directly proportional

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

Why is current through a filament lamp not directly proportional to the potential difference

A

because the filament gets hot which causes resistance to increase.
at high temps, the atoms in the filament vibrate more so electrons in the current now collide more with atoms so more energy is needed to push the current through filament

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

as potential difference increases, the current______

A

the current does NOT increase as much

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

the current through a diode___

A

flows in one direction only

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

why does current through a diode flow i only 1 direction?

A

it has a v high resistance in the reverse direction

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

what are diodes useful for?

A

controlling the flow of current

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

what does an LED do when current flows through it?

A

gives off light

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

why are LEDs useful?

A

theyre extremely energy efficient sources of light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

resistors in series___

A

add together because current must pass through each resistor and cant bypass any resistor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

whats it called when we replace two resistors which add to 150 ohms with a 15oo ohm resisitor

A

equivalent resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

the total resistance in parallel is less than:

A

the resistance of the smallest individual resistor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

why is the total resistance in parallel less than the resistance of the smallest individual resistor?

A

because theres two pathways for the current to take so more total current will flow through the circuit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

in parallel, if the current has increased but the potential difference hasn’t changed, what does that mean for the resistance?

A

total resistance must have decreased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

whats the resistance like in an LDR in dark conditions?

A

high resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

whats the resistance like in an LDR in light conditions?

A

very low

41
Q

whats an example of an LDR

A

a mobile phone turning the screen off during a conversation

42
Q

in the light, the resistance of the LDR is very low, meaning what?

What does that mean for the potential difference?

A

it takes v little energy for the current to pass through the LDR

its low

43
Q

(LDR) because potential difference is shared between components in series, the potential difference across the lamp is_

A

large so lamp now lights up screen

44
Q

explain how a phone screen lights up using an LDR

A

if held to a persons ear, LDRs in darkness, the resistance of the LDR rises sharply now it requires a great deal of energy for current to pass through ldr so potential difference across the LDR is v high meaning less electrical energy is available for the lamp. potential difference across lamp is v low meaning lamp becomes v dim

45
Q

in a thermistor, the resistance of a thermistor decreases, if the temp___

A

increases

46
Q

under cool conditions whats resistance like in a thermistor

A

The resistance of the thermistor is high meaning it takes lots of energy for the current to pass through , this causes high potential difference

47
Q

how is a thermistor related to a fan in low temps

A

in low temps, The resistance of the thermistor is high meaning it takes lots of energy for the current to pass through, this causes a high potential difference,, bc the potential difference is shared, potential difference across fan is small meaning the fan operates at v low speed

48
Q

how is a thermistor related to a fan in high temps

A

if the computer gets hot, the resistance of the thermistor falls now it takes much less energy for the current to pass through the thermistor meaning potential difference across the thermistor is now low so more electrical energy is available for fan making p.d across fan v high so fan powers to high speeds, cooling computer high

49
Q

how does an incubator for premature babies work

A

if the temperature falls, this is sensed by the thermistor, this causes a lamp to turn on and an alarm to sound

50
Q

what’s the method of the resistance required practical

A

attach the wire to a metre ruler using tape, and connect wire to rest of circuit using two crocodile clips (only wire between two clips is part of the circuit) move clips further apart and continue calculating resistance

51
Q

in resistance required prac, the resistance of the wire is_____ to the length

A

directly proportional

52
Q

what is a zero error

A

when a reading on a measuring instrument should be zero, this is a systematic error which means we cant reduce it by carrying out repeats

53
Q

in the case of resistance, how do you bypass the zero error?

A

subtract the zero error from all readings

54
Q

how does the zero error occur in the resistance required practical

A

its v difficult to get crocodile clip exactly at zero

there is some resistance caused by the contact between the crocodile clip and the wire

55
Q

how do heating effects change the results of resistance practical

A

if the temperature of the wire increases, the temperature also increases

56
Q

how to reduce heating effects in resistance required practical

A

using a low potential difference - this will keep the current low reducing any heating in the wire

only turn on the current when taking readings, turn off between readings

57
Q

what does a variable resistor contain

A

a long piece of wire and a coil, using a slider, we can change the length of the wire that the coil runs through

58
Q

why do we use a variable resistor

A

to control potential differences across the lamp
by increasing resistance we can make lamp dimmerl

59
Q

whats the method for the current required practical

A

connect the battery to the resistor using wires, a resistor in series with an ammeter and a variable resistor and voltmeter in parallel across the resistor.
use vm to read p.d across the resistor.
Then use ammeter to read current through the resistor, record in table.

Adjust variable resistor and record new readings on vm and am

do this several times to get range of readings.

Switch direction of battery meaning p.d is reversed, vm and am have negative values, take several readings and plot graph ( I against p.d)

60
Q

current through resistor is ______ to potential difference

this is only seen if ______ is kept _______

A

directly proportional
(resistor is ohmic conductor)

temperature, constant

61
Q

how does required practical for current change with a diode

A

an extra resistor because diodes are veery easily damaged by a high current, extra resistor keeps current relatively low to protect diode

Because of this we need a sensitive ammeter (milliammeter) (then adjust the variable resistor and record p.d and current do in forward and reverse direction

62
Q

in case of diode, we only get current wen the potential difference is around _______ volts

as p.d rises above this, the current ____

A

0.6-0.7

rises sharply

63
Q

in a diode , we get _______ if the p.d is ________

why?

A

no current, reversed

in reverse direction, the diode has a high resistance

64
Q

in things like blenders and fans, wheres the energy transfer?

A

electrical energy –> kinetic energy of motors

65
Q

in things like irons or kettles, wheres the energy transfer?

A

electrical energy –> thermal energy

66
Q

in things like hair dryers and washing machines, where is the energy transfer?

A

electrical energy —> kinetic energy of motors & thermal energy

67
Q

what is power

A

the rate at which energy is transferred

68
Q

appliances designed to produce thermal energy tend to have ____ power rating than appliances designed to produce kinetic energy

A

a much higher

69
Q

whats the equation for energy

A

energy = power x time

70
Q

whats equation for power

A

power = voltage x current

71
Q

whats a direct current

A

when current from the cell only moves in 1 direction

72
Q

whats alternating current?

A

when the current is constantly changing direction

73
Q

whats the main benefit of AC

A

its v easy to use a transformer to increase/decrease potential difference

74
Q

whats the frequency of uks alternating current

A

50 Hz

75
Q

whats the UK’s potential difference

A

230V

76
Q

what does the height of the peak tell us in an oscillascope

A

the maximum potential difference

77
Q

in an oscilloscope with a DIRECT current the potential difference ______

A

does not change

78
Q

how to find the frequency from a voltage-time graph (oscillascope)

A

1/time between peaks

79
Q

whats the brown wire in a plug and what does it do

A

the live wire

carries alternating potential difference from the supply

80
Q

whats the live wire connected to in the plug?

A

the fuse

81
Q

whats the blue wire and what does it do

A

the neutral wire

completes the circuit
p.d of neutral is 0V compared to live

82
Q

whats the green/ yellow striped wire and what does it do

A

the earth wire
this is a safety wire to stop the appliance from becoming live

83
Q

why can appliances with a metal case be dangerous?

A

if the live wire comes loose and touches the metal case, the case can become live
(could give fatal shock)

84
Q

why does can touching the live wire we fatal

A

current would flow through the person into the earth and theyd be electrocuted

85
Q

how does an earth wire work

A

earth wires attached to the metal case of the appliance and is connected into the ground with a metal rod so if case becomes live, a huge current flows to earth, the fuse melts and shuts off the circuit (preventing shock)

86
Q

whats the national grid

A

a system of transformers and high voltage cables

87
Q

whats the issue with electricity in homes

A

energy is always lost in the power cables due to the resistance of the wires

88
Q

how can we reduce energy lost from power stations to homes

A

building power stations near to homes

89
Q

what does a step up transformer do

A

increases the potential difference to several hundered so that less energy is lost in power cable

90
Q

what happens in a step down transformer

A

reduces voltage to 230V to be safer

91
Q

why are metals good conductors

A

electrons can easily pass through them

92
Q

what happens in a vanderwhatever generator

A

as belt moves, electrons pass from top plastic roller onto the belt

as electrons moves to bottom roller, electrons pass off the belt and are transferred to earth

so top region of generator becomes positively charged

positive charge builds up on metal dome

93
Q

why does hair go static when touching generator

A

man holding onto dome has overall positive charge, hairs on head are + so repel each other and move apart

94
Q

whats an example of static electricity being dangerous

A

electrostatic charge can build up as fuel flows through a refuelling pipe, this could cause a spark and trigger an explosion

95
Q

how to prevent aeroplane and refueling trucks from exploding?

A

They’re both earthed. this prevents any charges from building up and leading to spark

96
Q

when two insulators are rubbed together electrons can___

A

pass from one to the other

97
Q

what type of force is the force of attraction?

A

non contact as two spheres arent touching

98
Q

how do scientist show an electric field

what angle must they be touching the centre

A

field lines

90’

99
Q

if you decrease the distance between objects (field lines) what happens

A

the forces get stronger

GCSE Physics <3 (12 decks)

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