Electricity Flashcards
(123 cards)
1
Q
What is the unit for current?
A
Amperes, A
2
Q
What is the unit for charge?
A
Coulombs, C
3
Q
What is the unit for voltage?
A
Volts, V
4
Q
What IS current?
A
the rate of flow of charge
5
Q
What is the unit for energy?
A
Joules, J
6
Q
What is the unit for resistance?
A
Ohms, Ω
7
Q
What IS voltage?
A
energy transferred per unit charge, joules per coulomb
8
Q
What is the unit for power?
A
Watts, W
9
Q
What is the equation for charge?
A
charge = current x time (Q=IT)
10
Q
What is the equation for resistance, voltage and current?
A
voltage = current x resistance (V=IR)
11
Q
What is the equation for power?
A
power = current x voltage (P=IV)
12
Q
What is the equation for energy transferred?
A
energy transferred = power (IV) x time (E=PT)
13
Q
Mains electricity has an…current
A
alternating current
14
Q
Batteries have a…current
A
direct current
15
Q
What happens to the current when you increase the resistance?
A
less current can flow
16
Q
What colour is the neutral wire?
A
blue
17
Q
What colour is the live wire?
A
brown
18
Q
What colour is the earth wire?
A
green and yellow
19
Q
What are the safety features of a plug (the plug itself)?
A
- right coloured wire connected to each pin- no bare wires showing inside plug- cable grip tightly fastened over the cable outer layer- metal parts made of copper or brass (good conductors)- case, cable grip and cable insulation made of rubber or plastic (good insulators and flexible)
20
Q
Order of wires in a plug?
A
neutral, earth, live
21
Q
What does the neutral wire do?
A
current flows out of the neutral wire, which always has 0V
22
Q
What does the live wire do?
A
current flows in via the live wire, which alternates between a high negative and positive (alternating) voltage of 230V
23
Q
What does the earth wire do?
A
when there is a fault and the live touches the case, a large current builds up in the live, through the case and is sent down the earth wire.
24
Q
Safety precautions when using plugs?
A
- damaged (missing/ cracked/ broken case) so that there aren’t exposed live wires which could give you a shock- cable isn’t frayed, exposed live wires- cables aren’t too long, trip hazard- no water near electrics, good conductor- no metal objects in plug as good conductor
25
A plug with metal casing...
must be earthed to an earth wire so that the conductor can never become live
26
A plug with plastic casing...
is double insulated. Plastic is an insulator so stops current flowing. Doesn't need an earth wire.
27
What does a fuse do?
when a fault develops, a surge of current flows though the live and then the earth. This melts the fuse which cuts off the live supply. This isolates the appliance which means you can't get shocked and reduces the fire risk
28
What does a circuit breaker do?
when a circuit breaker detects a surge in current it breaks the circuit by opening a switch
29
What are the advantages of a circuit breaker over a fuse?
- works faster- doesn't have to be replaced, can be reset- works for small current charges which might not melt a fuse but are still dangerous
30
What is an RCCB?
residual current circuit breaker, detects a difference in current between the neutral and the live wire and cuts the circuit
31
What happens when electric current passes through a resistor?
there is a heating effect on the resistor which increases the resistor's resistance, meaning less current can flow.
32
What are the advantages of the heating effect due to a current in a resistor?
- melts fuses- can be used in toasters to cook bread
33
What IS power?
the rate of energy transfer
34
What do you need to know to work out a fuse rating?
current
35
An ammeter must be placed in...
series
36
A voltmeter must be placed in...
parallel
37
the gradient of an I-V graph is...
1/Resistance
38
Metal filament lamp I-V graph
as temperature increases, resistance increases, hence curve.
39
Wire I-V graph
current at a contant temp is proportional to voltage
40
Diode I-V graph
current will only flow in one direction
41
Different resistors I-V graph
current through a resistor at a constant temp is proportional to voltage. Different resistors have different resistances, hence slope.
42
What is the unit for current?
Amperes, A
43
What is the unit for charge?
Coulombs, C
44
What is the unit for voltage?
Volts, V
45
What IS current?
the rate of flow of charge
46
What is the unit for energy?
Joules, J
47
What is the unit for resistance?
Ohms, Ω
48
What IS voltage?
energy transferred per unit charge, joules per coulomb
49
What is the unit for power?
Watts, W
50
What is the equation for charge?
charge = current x time (Q=IT)
51
What is the equation for resistance, voltage and current?
voltage = current x resistance (V=IR)
52
What is the equation for power?
power = current x voltage (P=IV)
53
What is the equation for energy transferred?
energy transferred = power (IV) x time (E=PT)
54
Mains electricity has an...current
alternating current
55
Batteries have a...current
direct current
56
What happens to the current when you increase the resistance?
less current can flow
57
What colour is the neutral wire?
blue
58
What colour is the live wire?
brown
59
What colour is the earth wire?
green and yellow
60
What are the safety features of a plug (the plug itself)?
- right coloured wire connected to each pin- no bare wires showing inside plug- cable grip tightly fastened over the cable outer layer- metal parts made of copper or brass (good conductors)- case, cable grip and cable insulation made of rubber or plastic (good insulators and flexible)
61
Order of wires in a plug?
neutral, earth, live
62
What does the neutral wire do?
current flows out of the neutral wire, which always has 0V
63
What does the live wire do?
current flows in via the live wire, which alternates between a high negative and positive (alternating) voltage of 230V
64
What does the earth wire do?
when there is a fault and the live touches the case, a large current builds up in the live, through the case and is sent down the earth wire.
65
Safety precautions when using plugs?
- damaged (missing/ cracked/ broken case) so that there aren't exposed live wires which could give you a shock- cable isn't frayed, exposed live wires- cables aren't too long, trip hazard- no water near electrics, good conductor- no metal objects in plug as good conductor
66
A plug with metal casing...
must be earthed to an earth wire so that the conductor can never become live
67
A plug with plastic casing...
is double insulated. Plastic is an insulator so stops current flowing. Doesn't need an earth wire.
68
What does a fuse do?
when a fault develops, a surge of current flows though the live and then the earth. This melts the fuse which cuts off the live supply. This isolates the appliance which means you can't get shocked and reduces the fire risk
69
What does a circuit breaker do?
when a circuit breaker detects a surge in current it breaks the circuit by opening a switch
70
What are the advantages of a circuit breaker over a fuse?
- works faster- doesn't have to be replaced, can be reset- works for small current charges which might not melt a fuse but are still dangerous
71
What is an RCCB?
residual current circuit breaker, detects a difference in current between the neutral and the live wire and cuts the circuit
72
What happens when electric current passes through a resistor?
there is a heating effect on the resistor which increases the resistor's resistance, meaning less current can flow.
73
What are the advantages of the heating effect due to a current in a resistor?
- melts fuses- can be used in toasters to cook bread
74
What IS power?
the rate of energy transfer
75
What do you need to know to work out a fuse rating?
current
76
An ammeter must be placed in...
series
77
A voltmeter must be placed in...
parallel
78
the gradient of an I-V graph is...
1/Resistance
79
Metal filament lamp I-V graph
as temperature increases, resistance increases, hence curve.
80
Wire I-V graph
current at a contant temp is proportional to voltage
81
Diode I-V graph
current will only flow in one direction
82
Different resistors I-V graph
current through a resistor at a constant temp is proportional to voltage. Different resistors have different resistances, hence slope.
83
What is the unit for current?
Amperes, A
84
What is the unit for charge?
Coulombs, C
85
What is the unit for voltage?
Volts, V
86
What IS current?
the rate of flow of charge
87
What is the unit for energy?
Joules, J
88
What is the unit for resistance?
Ohms, Ω
89
What IS voltage?
energy transferred per unit charge, joules per coulomb
90
What is the unit for power?
Watts, W
91
What is the equation for charge?
charge = current x time (Q=IT)
92
What is the equation for resistance, voltage and current?
voltage = current x resistance (V=IR)
93
What is the equation for power?
power = current x voltage (P=IV)
94
What is the equation for energy transferred?
energy transferred = power (IV) x time (E=PT)
95
Mains electricity has an...current
alternating current
96
Batteries have a...current
direct current
97
What happens to the current when you increase the resistance?
less current can flow
98
What colour is the neutral wire?
blue
99
What colour is the live wire?
brown
100
What colour is the earth wire?
green and yellow
101
What are the safety features of a plug (the plug itself)?
- right coloured wire connected to each pin- no bare wires showing inside plug- cable grip tightly fastened over the cable outer layer- metal parts made of copper or brass (good conductors)- case, cable grip and cable insulation made of rubber or plastic (good insulators and flexible)
102
Order of wires in a plug?
neutral, earth, live
103
What does the neutral wire do?
current flows out of the neutral wire, which always has 0V
104
What does the live wire do?
current flows in via the live wire, which alternates between a high negative and positive (alternating) voltage of 230V
105
What does the earth wire do?
when there is a fault and the live touches the case, a large current builds up in the live, through the case and is sent down the earth wire.
106
Safety precautions when using plugs?
- damaged (missing/ cracked/ broken case) so that there aren't exposed live wires which could give you a shock- cable isn't frayed, exposed live wires- cables aren't too long, trip hazard- no water near electrics, good conductor- no metal objects in plug as good conductor
107
A plug with metal casing...
must be earthed to an earth wire so that the conductor can never become live
108
A plug with plastic casing...
is double insulated. Plastic is an insulator so stops current flowing. Doesn't need an earth wire.
109
What does a fuse do?
when a fault develops, a surge of current flows though the live and then the earth. This melts the fuse which cuts off the live supply. This isolates the appliance which means you can't get shocked and reduces the fire risk
110
What does a circuit breaker do?
when a circuit breaker detects a surge in current it breaks the circuit by opening a switch
111
What are the advantages of a circuit breaker over a fuse?
- works faster- doesn't have to be replaced, can be reset- works for small current charges which might not melt a fuse but are still dangerous
112
What is an RCCB?
residual current circuit breaker, detects a difference in current between the neutral and the live wire and cuts the circuit
113
What happens when electric current passes through a resistor?
there is a heating effect on the resistor which increases the resistor's resistance, meaning less current can flow.
114
What are the advantages of the heating effect due to a current in a resistor?
- melts fuses- can be used in toasters to cook bread
115
What IS power?
the rate of energy transfer
116
What do you need to know to work out a fuse rating?
current
117
An ammeter must be placed in...
series
118
A voltmeter must be placed in...
parallel
119
the gradient of an I-V graph is...
1/Resistance
120
Metal filament lamp I-V graph
as temperature increases, resistance increases, hence curve.
121
Wire I-V graph
current at a contant temp is proportional to voltage
122
Diode I-V graph
current will only flow in one direction
123
Different resistors I-V graph
current through a resistor at a constant temp is proportional to voltage. Different resistors have different resistances, hence slope.
