Brainscape's Knowledge GenomeTM

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


See full index

Physics GCSE > Section 5 - Current and Circuits > Flashcards

Section 5 - Current and Circuits 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

What is current?

A

The flow of electric charge around the circuit

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

What is the charge equation?

A 
Charge = Current x Time
Coulombs = Amps x Seconds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

A battery passes a current of 0.25A through a light bulb over a period of 4 hours
How much charge does the battery transfer altogether?

A 
Q = C x T
Q = 0.25 x 4(60x60)
Q = 3600C
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Calculate how long it takes a current of 2.5A to transfer a charge of 120C

A 
Q = C x T
T = Q / C
T = 120 / 2.5
T = 48s
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is potential difference?

A

The energy transferred per coulomb of charge

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

What is the energy transferred equation?

A 
Energy = Charge x Potential Difference
Joules = Coulombs x Volts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the potential difference equation?

A 
Voltage = Current x Resistance
Volts = Amps x Ohms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

A 4 ohm resistor in a circuit has a potential difference of 6.0 V across it
What is the current through the resistor?

A 
V = I x R
I = V / R
I = 6 / 4
I = 1.5 A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does resisitance often cause?

A

An increase in temperature

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

Why does resisitance increase heat?

A

When the electrons collide with the ions in the lattice that make up the resistor the ions gain energy which causes them to heat

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

Give one exception where resistance decreases with heat?

A

Thermistor

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

What usually happens when the resistor gets too hot?

A

No current will be able to flow

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

A current flowing through a resistor transfer 360 J of energy when 75 C of charge are passed through it
Calculate the PD across the resistor

A 
E = Q x V
V = E / Q
V = 360 / 75
V = 4.8 V
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does a standard test circuit include?

A

Ammeter
Energy Source (eg. Battery)
Voltmeter
Component

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

How do you use a standard test circuit?

A

Change the voltage and make readings from the ammeter and voltmeter and plot graph

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

When testing the standard test circuit, what must you stop from happening?

A

The circuit getting too hot as it will affect results

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

What does a diode do?

A

Acts as a one-way switch for the current

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

What should you see when investigating thermistors?

A

As you heat the thermistor, the current through the thermistor increases as the resistance decreases

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

What should you see when investigating LDR’s?

A

As the light gets brighter, the current increases as the resistance decreases

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

Describe a resistor IV graph?

A

Directly proportional

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

Describe a wire IV graph?

A

Directly proportional

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

Describe a filament IV graph?

A

S shape

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

Describe a diode IV graph?

A

Exponential in one direction (curver above x axis only)

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

What are linear components?

A

Components that have an IV graph that’s a straight line

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

What are non-linear components?

A

Components that have an IV graph that is curved

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

How do LDRs affect resistance?

A

In bright light the resistance falls, in darkness the resistance is highest

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

What are LDRs used in?

A

Automatic night lights
Outdoor lighting
Burgular detectors

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

How do thermistors affect resistance?

A

In hot conditions the resistance drops, in cool conditions the resistance goes up

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

What are thermistors used in?

A

Temperature detectors
Car Engine sensors
Thermostats

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

Describe a series circuit?

A

A circuit of components connected in a line, end to end

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

What is wrong with a series circuit?

A

IF you remove, break or disconnect one component the circuit will stop

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

What are the rules behind a series circuit?

A

The current is the same everywhere
The voltage is shared between the componenets
The total resistance increases as you increase resistors

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

Describe a parallel circuit?

A

A circuit of components where they are separately connect

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

What are always connected in series?

A

Ammeters

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

What are the rules behind a parallel circuit?

A

The voltage is the same across all components
The current is shared between he branches
The total resistance of the circuit decreases if you add a second resisitor in parallel

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

A filament lamp and a resistor are connected in series
A current of 0.5A flow through the lamp
State the current flowing through the resisitor?

A

0.5 A

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

What happens in series when you add resistors?

A

The total resistance increases

38
Q

Why does the resistance of a series circuit increase when you add resistors?

A

The voltage is being shared across more components, so there will be lower voltage through each resistor therefore the current will also be lower

39
Q

What happens in parallel when you add resistors?

A

The total resistance decreases

40
Q

Why does the resistance of a parallel circuit decrease when you add resistors?

A

Another loop will be added therefore the current will have an extra way to go which means the total current will increase therefore there will be a decrease in the total resistance

41
Q

A 12V cell is connected in series with a 2ohm resistor, a 3ohm resistor and a 7ohm resistor
Calculate the current going through

A 
V = I x R
I = V / R
I = 12 / (3+2+7)
I = 12 / 12
42
Q

What happens when an electrical charge goes through a change in potential difference?

A

Energy is transferred

43
Q

Why is energy transferred when a charge changes voltage?

A

Work is done against resistance

44
Q

What is the energy transferred equation?

A 
E = I x V x t
Energy = Current x Voltage x Time
45
Q

What do fuses do?

A

Protect the circuits by melting if the current gets too high

46
Q

How can heating from a circuit be good?

A

In toasters/bulbs/heaters, where a extremely resistant coil has electricity passed through it which gives off infrared radiation

47
Q

A laptop charger is connected to a 230 V source for an hour
A current of 8.0 A flows through it
Calculate the energy transferred by the laptop charger

A 
E = I x V x t
E = 8 x 230 x (60x60)
E = 6,624,000 J
48
Q

What does energy transferred depend on?

A

How long the appliance is in for and its power

49
Q

What is the power equation?

A

Power = Energy / Time

50
Q

Which transfers more energy in the same time?
A 500W microwave
A 750W microwave

A

The 750W microwave

51
Q

What is the voltage of a charge?

A

The amount of energy each unit of charge transfers

52
Q

What is the power equation (IV)

A 
P = I x V
Power = Current x Voltage
53
Q

A 1 kW hair dryer is connected to a 230V supply

Find the fuse needed?

A 
P = I x V
P / V = I
1000 / 230 = I
4.3 A 
therefore a 5 A fuse is needed
54
Q

What is the power equation (IR)?

A 
P = I² x R
Power = Current² x Resistance
55
Q

Calculate the difference in the amount of energy transferred by a 250 W TV and 375 W TV when they are both use for two hours?

A 
P = E / t
250 x (2x60x60) = E1
1,800,000 = E1
375 x (2x60x60) = E2
2,700,000 = E2
E2 - E1 = 900,000
56
Q

What is AC?

A

Movement of charge in a constantly changing direction

57
Q

What produces alternating currents?

A

Alternating voltages

58
Q

What is the voltage inside the house?

A

230V

59
Q

What is the frequency of the house AC?

A

50Hz

60
Q

What supply direct current?

A

Batteries and cells

61
Q

What creates DC?

A

Direct Voltage

62
Q

What colour is the live wire?

A

Brown

63
Q

What is the live wire

A

The wire that carries the voltage

64
Q

What colour is the neutral?

A

Blue

65
Q

What is the neutral wire?

A

The wire that completes the circuit

66
Q

What is the voltage of the blue wire?

A

0V

67
Q

When does the blue wire have a current?

A

When the appliance is working normally

68
Q

What colour is the earth wire?

A

Green and yellow

69
Q

What is the earth wire?

A

The wire for safety and protection

It carries the current away if something goes wrong

70
Q

What is the voltage of the earth wire?

A

0V

71
Q

What is the voltage of the live wire?

A

230V

72
Q

Explain the difference between a.c and d.c electricity supplies?

A

In AC the movement of the charges constantly changes whilst in a direct current supply the movement of the charges is only in one direction

73
Q

What do earthing and fuses prevent?

A

Electrical overloads

74
Q

What can current surges lead to?

A

Melting, fire or electric shocks

75
Q

What is a fault?

A

Where the live wire touches the metal case

76
Q

What do circuit breakers do?

A

Instead of melting, a large current simply shuts it off

77
Q

What are the advantages of circuit breakers?

A

Can be reused and much quicker than fuses

78
Q

What are the disadvantages of circuit breakers?

A

Expensive

79
Q

What doesn’t need an earth wire?

A

A double insulated appliance

80
Q

Which wire are fuses connect to?

A

The Live wire

81
Q

Name one linear component and one non-linear component?

A

Resistor and diode

82
Q

What happens to the resistance of a thermistor as it gets hotter?

A

It decreases

83
Q

How does the current in each component differ?

A

Based off the resistance in the components

84
Q

How does potential difference vary in parallel?

A

Total amount shared inside each branch

85
Q

How does adding resistors in parallel affect the resisitance?

A

It decreases it

86
Q

Give two disadvantages of the heating effect?

A

Inefficient and can break circuit

87
Q

Give two advantages of the heating effect?

A

Can be made into useful energy (bulb or heater) and can be used in fuse

88
Q

What is a power rating

A

The power that flows through the componenet

89
Q

Why are the three wires in a three-core cable coloured?

A

Avoid confusion which could lead to shocks

90
Q

Give the potential difference for the three wires?

A

Live - 230 V
Neutral - 0 V
Earthed - 0 V

91
Q

Explain why touching a live wire is dangerous?

A

The wire has 230 V which will flow through you to reach earth

92
Q

Explain how a fuse works?

A

If the current gets too hot, the temperature will increase and melt the fuse, stopping the circuit from working

Physics GCSE (7 decks)

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