Paper 1 Electricty Flashcards
1
Q
What do circuit diagrams represent?
A
Circuits for electrons to flow through
Circuit diagrams are visual representations of electrical circuits, showing how components are connected.
2
Q
What is the simplest type of circuit?
A
A simple circle
This refers to basic circuit designs that can be expanded into more complex layouts.
3
Q
What are batteries made up of?
A
Two or more cells
Cells are the individual units that store and provide electrical energy, while batteries are collections of these cells.
4
Q
What symbol represents a filament lamp?
A
A small lightbulb
Filament lamps are common components in circuits, used to indicate light sources.
5
Q
What does a switch do in a circuit?
A
Can be closed or open
A closed switch allows current to flow, while an open switch interrupts the flow.
6
Q
What is current a measure of?
A
The flow of electrons
Current is analogous to the flow of water through a pipe.
7
Q
What is current measured in?
A
Amperes (A)
The unit of current, named after André-Marie Ampère.
8
Q
What does potential difference refer to?
A
Voltage
Voltage is the driving force that pushes electrons through a circuit.
9
Q
What is potential difference measured in?
A
Volts
The unit for measuring voltage, named after Alessandro Volta.
10
Q
What does resistance do in a circuit?
A
Resists the flow of electrons
Resistance can be compared to a partial blockage in a pipe, impeding the flow.
11
Q
What is resistance measured in?
A
Ohms
The unit for measuring electrical resistance, named after Georg Simon Ohm.
12
Q
How is the positive terminal represented in a circuit diagram?
A
By a longer line
The positive terminal of a cell or battery is indicated by a longer line compared to the negative terminal.
13
Q
What direction do electrons flow in a circuit?
A
From the negative terminal to the positive terminal
This is due to the negative charge of electrons, which move towards the positive charge.
14
Q
What was the historical convention regarding current flow?
A
Current flows from positive to negative
This convention was established before the discovery of electron flow and is still used today.
15
Q
Fill in the blank: Current is often noted with the letter _______.
A
I
16
Q
Fill in the blank: Potential difference is noted by the letter _______.
A
V
17
Q
True or False: Conventional current flows from the negative terminal to the positive terminal.
A
False
Conventional current is defined as flowing from positive to negative.
18
Q
What does the equation V = IR represent?
A
Potential difference or voltage equals current times resistance.
19
Q
If a 24 V battery produces a current of 8 A, what is the resistance?
A
3 Ohms.
20
Q
What happens to current when voltage increases while resistance stays constant?
A
Current increases proportionally.
21
Q
True or False: The graph of current versus potential difference is straight for circuits with constant resistance.
A
True.
22
Q
What happens to the resistance if the temperature increases?
A
Resistance increases.
23
Q
Fill in the blank: A filament lamp contains a very thin metal _______.
A
filament.
24
Q
What occurs to the filament in a filament lamp as current flows through it?
A
It heats up until it has massive resistance.
25
Devices that only allow current to flow in one direction have high resistance in _______ direction.
reverse.
26
What does a larger resistor in a circuit indicate about potential difference?
A larger potential difference is required to drive the same current.
27
As current increases in a filament lamp, what happens to the resistance?
Resistance increases.
28
In circuits with only wires or resistors, how does the line on the graph appear?
Straight.
29
What is the primary relationship described by the equation V = IR?
The relationship between voltage, current, and resistance.
30
If resistance stays constant and we use a bigger battery, what happens to the current?
Current increases.
31
What is charge a measure of?
The total current that flowed within a certain period of time
## Footnote
Charge can be likened to the total amount of water flowing down a river over time
32
How is charge represented in formulas?
With a Q
## Footnote
Charge is a fundamental quantity in electrical physics
33
In which unit is charge measured?
Coulombs (C)
## Footnote
The coulomb is the SI unit for electric charge
34
What is the equation to calculate charge?
Charge = Current (in Amps) × Time (in seconds)
## Footnote
This equation relates charge, current, and time directly
35
What is the charge that flows through a wire if the current is 12 Amps for 50 seconds?
600 Coulombs
## Footnote
Calculation: 12 A × 50 s = 600 C
36
Fill in the blank: Charge equals ______ multiplied by time.
Current
## Footnote
Current is measured in Amperes (A)
37
If a phone charger transfers a total charge of 43.2 kg over two hours, what is the first step to find the current?
Convert 43.2 kg to Coulombs by multiplying by 1000
## Footnote
1 kg of charge is equivalent to 1000 Coulombs
38
How many seconds are there in two hours?
7200 seconds
## Footnote
2 hours = 2 × 60 minutes × 60 seconds
39
What is the formula to find current when charge and time are known?
Current = Charge ÷ Time
## Footnote
This rearrangement of the charge equation allows for current calculation
40
What current flows through the wire if a charger transfers 43,200 Coulombs in 7200 seconds?
6 Amps
## Footnote
Calculation: 43,200 C ÷ 7200 s = 6 A
41
What is the function of a switch in a circuit?
A switch can be closed to allow electricity to flow or opened to turn off the circuit.
42
What happens to a fuse when too much current flows through a circuit?
A fuse breaks and stops the flow of current.
43
What direction does current flow through a fuse?
Current only flows in one direction through a fuse.
44
What type of bulbs are commonly used in alarm clocks and traffic lights?
LED bulbs.
45
What is the purpose of an ammeter in a circuit?
An ammeter measures current.
46
What does a voltmeter measure?
A voltmeter measures potential difference and is connected in parallel.
47
What are the two types of resistors mentioned?
Fixed resistors and variable resistors.
48
What is a light-dependent resistor (LDR)?
An LDR's resistance depends on the intensity of light.
49
What happens to the resistance of an LDR in bright light?
The resistance is very low, allowing lots of current to flow.
50
What is the use of LDRs in practical applications?
LDRs can be used in automatic nightlights and alarms.
51
What is the relationship between temperature and the resistance of thermistors?
Higher temperatures cause the resistance to fall, while lower temperatures increase resistance.
52
Fill in the blank: A special type of diode is called a _______.
LED.
53
True or False: Resistors can only be fixed and cannot be variable.
False.
54
What type of circuit component allows for modification of resistance?
Variable resistors.
55
How does the resistance of a thermistor change with temperature?
Resistance decreases with higher temperatures and increases with lower temperatures.
56
What is the main difference between series and parallel circuits?
In series circuits, components are connected in a single loop; if one disconnects, the whole circuit stops working.
## Footnote
In parallel circuits, multiple paths exist for current flow, and one component can fail without affecting the others.
57
How is the total voltage in a series circuit related to individual components?
The total voltage is equal to the sum of the voltages across all individual components.
## Footnote
For example, if a battery has a potential difference of 12 V, the voltages across components must add up to 12 V.
58
If one lamp in a series circuit measures 8 V, what is the voltage across the other lamp?
4 V
## Footnote
This is because the total voltage must equal 12 V.
59
What is the equation to calculate current in a circuit?
Current can be calculated by dividing the total potential difference by the total resistance.
## Footnote
This is derived from Ohm's Law, I = V/R.
60
What is the total resistance in a series circuit with resistors of 4 ohms and 2 ohms?
6 ohms
## Footnote
This is calculated by adding the individual resistances (4 + 2).
61
When measuring current, where should the ammeter be placed?
The ammeter should be placed in series with all components.
## Footnote
Placing it in parallel will not give accurate readings.
62
How do you calculate the voltage across a specific component in a series circuit?
Multiply the current by the resistance of that component.
## Footnote
This follows the formula V = I × R.
63
In a series circuit with a total voltage of 12 V and a component with 4 ohms resistance, what is the voltage across that component if the current is 2 A?
4 V
## Footnote
This is calculated using V = I × R (2 A × 2 ohms = 4 V).
64
What happens to the voltage across components with higher resistance in a series circuit?
Components with greater resistance will have a higher share of the voltage.
## Footnote
This is due to Ohm's Law, where more force is needed to push charge through higher resistance.
65
True or False: In a series circuit, the current is the same across all components.
True
## Footnote
The current remains constant throughout a series circuit.
66
Fill in the blank: The potential difference must be ______ across each component in a series circuit.
shared
## Footnote
This means that the total voltage is distributed among the components.
67
What is a key characteristic of parallel circuits regarding components?
Each component has its own loop
## Footnote
This means if one component fails, the other components remain functional.
68
In a parallel circuit, what happens to the potential difference across each component?
Each component gets the full source potential difference
## Footnote
For example, with a 12 V battery, all components receive 12 V.
69
How is the current distributed in a parallel circuit?
The current is shared between all loops
## Footnote
The distribution depends on the resistance of the individual components.
70
If a parallel circuit has a total of 4 A flowing, how could the current be split between two loops?
Possible splits include 3 A in one loop and 1 A in the other, or 2 A in each loop
## Footnote
The sum of currents in each loop equals the total current.
71
What analogy is used to explain how current flows in a parallel circuit?
Water flowing down a hill
## Footnote
Lower resistance paths allow more current to flow, similar to how water flows more easily down paths with less resistance.
72
What happens to the total resistance of a parallel circuit as more components are added?
The total resistance decreases
## Footnote
This is counterintuitive but can be understood as increasing pathways for current flow.
73
Fill in the blank: In parallel circuits, loops with greater resistance take a _______ share of the current.
lower
74
True or False: In a parallel circuit, if one component breaks, the entire circuit fails.
False
## Footnote
Only the broken component stops functioning; others remain intact.
75
What is the relationship between current and resistance in a parallel circuit?
Higher current flows through lower resistance loops
## Footnote
This is analogous to water flowing more freely through wider paths.
76
What is the total current in a parallel circuit equal to?
The sum of the currents in all loops
## Footnote
This reflects the conservation of charge in electrical circuits.
77
What is the effect of adding more loops to a parallel circuit?
Decreases total resistance
## Footnote
More pathways for current flow make it easier for current to travel.
78
What is the national grid?
A giant network of transformers and wires spread across the country to distribute electricity
## Footnote
The national grid ensures that electricity generated from various sources reaches consumers efficiently.
79
From what sources is electricity generated in the UK?
A range of different sources, primarily from power stations
## Footnote
This includes fossil fuels and nuclear power.
80
How do nuclear power stations generate electricity?
By generating heat and converting thermal energy into electrical energy
## Footnote
This process is crucial for the functionality of nuclear power stations.
81
When does electricity demand peak in the UK?
In the late afternoon and evening
## Footnote
This is typically when people return home from work, cook, and watch TV.
82
Why do power stations often run below their maximum power output?
To have lots of spare capacity for surges in demand
## Footnote
This helps ensure reliability during peak usage times.
83
What is the equation for power in terms of voltage and current?
Power = Voltage × Current
## Footnote
High power transmission requires high voltage and high current.
84
What problem arises when high current flows through a wire?
It generates lots of heat due to resistance
## Footnote
This results in energy loss to the surroundings.
85
What strategy is used to minimize energy loss during electricity transmission?
Keep the current low and increase the voltage high
## Footnote
This approach helps reduce heat generation in the wires.
86
What is the voltage to which electricity is stepped up for transmission?
Around 400,000 volts
## Footnote
This high voltage is crucial for efficient long-distance transmission.
87
What happens to the voltage before electricity reaches its final destination?
It is reduced back down by step-down transformers
## Footnote
This ensures safety and compatibility with household appliances.
88
What is the final voltage level for electricity used in homes?
230 volts
## Footnote
This voltage is safe for household use and appliances.
89
What role do transformers play in the national grid?
Step up voltage for transmission and step down voltage for safe usage
## Footnote
Transformers are essential for minimizing energy loss and ensuring safety.
90
True or False: High voltage is safe for household appliances.
False
## Footnote
High voltage can damage appliances and pose safety risks.
91
What are the two types of current?
Alternating current (AC) and direct current (DC)
## Footnote
AC is characterized by the direction of current constantly swapping back-and-forth, while DC flows in one direction.
92
How does alternating current (AC) behave?
The direction of the current constantly swaps back-and-forth
## Footnote
This means the charge flows in one direction and then the other direction repeatedly.
93
What is the frequency of the UK main supply electricity?
50 Hz
## Footnote
This means the potential difference fluctuates from positive 240 V to -240 V 50 times every second.
94
What is the typical voltage of the UK main supply electricity?
Around 240 V
## Footnote
It can also be 230 V, both are correct in the UK context.
95
What devices commonly use direct current (DC)?
Batteries and devices like phones or calculators
## Footnote
DC is produced by a constant positive or negative potential difference.
96
What is the behavior of direct current (DC)?
The charge is always flowing in the same direction
## Footnote
This is distinct from alternating current which fluctuates direction.
97
What equipment is used to display graphs of current and voltage?
Oscilloscope
## Footnote
An oscilloscope displays the waveform of electrical signals on a monitor.
98
Fill in the blank: The potential difference in an AC circuit fluctuates between _______.
positive and negative
## Footnote
This fluctuation is what characterizes alternating current.
99
True or False: In alternating current, the voltage is always a constant value.
False
## Footnote
The voltage fluctuates over time in AC.
100
What is the main supply voltage in the UK?
230 V
## Footnote
The main supply in the UK operates at a frequency of 50 Hz.
101
What is the frequency of the electricity supplied in the UK?
50 Hz
## Footnote
This frequency is standard for the national grid.
102
What type of cable is usually involved when plugging an appliance into a socket?
Three core cable
## Footnote
A three core cable contains three wires: live, neutral, and earth.
103
What material are the wires inside the cable typically made of?
Copper
## Footnote
Copper is used because it is an excellent conductor of electricity.
104
What is the purpose of the insulating plastic coating on wires?
Safety
## Footnote
The plastic insulation prevents accidental contact with live wires.
105
What color is the live wire in UK electrical systems?
Brown
## Footnote
The live wire provides the alternating potential difference.
106
What color is the neutral wire in UK electrical systems?
Blue
## Footnote
The neutral wire completes the circuit by carrying away current.
107
What is the potential difference of the neutral wire?
0 V
## Footnote
The neutral wire acts to return current without a potential difference.
108
What color is the earth wire in UK electrical systems?
Striped green and yellow
## Footnote
The earth wire's role is to prevent electric shock by providing a safe path to ground.
109
What is the potential difference of the earth wire?
0 V
## Footnote
The earth wire does not normally carry current.
110
What is the primary function of the earth wire?
To stop the casing from becoming live
## Footnote
This protects users from electric shock if a live wire touches the casing.
111
Why is it dangerous to touch plug sockets even when switched off?
A live wire can still have a potential difference
## Footnote
Contact with a live wire can result in an electric shock.
112
Fill in the blank: The live wire has a potential difference of _______.
230 V
113
True or False: The earth wire usually carries current.
False
## Footnote
The earth wire is designed to carry current only in fault conditions.
114
What happens if a live wire loses insulation and touches the casing?
It could electrify the casing
## Footnote
This creates a risk of electric shock to anyone who touches it.
115
What is a fuse?
A very thin piece of wire connected to the live wire that breaks the circuit when too much current flows through it.
## Footnote
The fuse melts and stops the current flow to prevent damage or hazards.
116
How does a fuse work?
It heats up quickly and melts when a surge of current flows through, breaking the circuit.
## Footnote
This prevents further current from flowing and reduces the risk of fire or electric shock.
117
What is the purpose of circuit breakers?
To break the circuit whenever there is a surge in current, but they can be easily reset instead of replaced.
## Footnote
Unlike fuses, circuit breakers do not need to be replaced after a surge.
118
What is a key difference between fuses and circuit breakers?
Fuses are permanently broken and need replacement; circuit breakers can be reset.
## Footnote
This makes circuit breakers more convenient but typically more expensive.
119
What is the function of an earth wire?
To provide an alternative pathway for current to flow away from a person and divert it to the ground.
## Footnote
This helps prevent electric shocks.
120
What does double insulation mean?
The entire appliance is covered in a plastic casing, preventing exposure to metal parts.
## Footnote
Appliances with double insulation do not require an earth wire.
121
Fill in the blank: A fuse is designed to break the circuit when the current exceeds _______.
[a specific rating, e.g., 5A or 13A]
122
True or False: Circuit breakers are cheaper than fuses.
False
## Footnote
Circuit breakers are generally more expensive than fuses.
123
What is one downside of using fuses?
They are permanently broken and must be replaced after use.
## Footnote
This can be inconvenient during power surges.
124
What happens when a surge wire comes loose?
It can cause appliances to touch the casing, leading to a risk of electric shock.
## Footnote
This highlights the importance of proper electrical installation.
125
What material does not conduct electricity, making it safe to touch?
Plastic
## Footnote
This is why plastic casings are used in double insulated appliances.
126
What factors can affect the resistance of a circuit?
The resistance can depend on:
* If components are in series or parallel
* The length of wire used in the circuit
## Footnote
Additional factors may include temperature and material of the wire.
127
What is the formula to calculate resistance in a circuit?
R = V ÷ I
## Footnote
This is derived from the equation V = IR.
128
What equipment is needed to investigate the effect of wire length on resistance?
You need:
* Ammeter
* Voltmeter
* Metre ruler
* Thin test wire
* Crocodile clips
* Switch
* Battery
## Footnote
Each component plays a role in measuring current and potential difference.
129
How should you measure the wire length in the experiment?
1) Attach a crocodile clip to the wire at 0 cm
2) Attach the second clip a short distance from the first
3) Write down the length between the clips
## Footnote
This ensures accurate measurements for different lengths.
130
What should you do after recording current and potential difference?
Calculate the resistance using R = V ÷ I
## Footnote
This step is crucial for analyzing the effect of wire length on resistance.
131
What should the graph of resistance against wire length look like?
It should be a straight line through the origin.
## Footnote
This indicates that resistance is directly proportional to wire length.
132
True or False: Opening the switch between readings can help reduce measurement errors.
True
## Footnote
This allows the circuit to cool down.
133
Fill in the blank: The longer the wire, the greater the _______.
resistance
## Footnote
This conclusion is based on the experiment's results.
134
What is the purpose of using a variable resistor in the circuit diagram?
To represent the test wire
## Footnote
This allows for adjustments in resistance during the experiment.
135
What is the first step in the investigation of wire length on resistance?
Attach a crocodile clip to the wire level with 0 cm on the ruler.
## Footnote
This sets the starting point for measuring wire length.
136
What happens to the resistance when components are arranged in series?
The total resistance increases.
## Footnote
In a series circuit, resistances add up.
137
What is the first step in setting up the basic circuit?
Find at least four identical resistors.
138
What should you do after building the circuit?
Read the current in the circuit (l) from the ammeter.
139
In the formula for the rate of the current, what does 'I' represent?
The current in the circuit.
140
What is the relationship between the potential difference (pd) in a series circuit and the battery?
The pd is the same as the pd of the battery.
141
What happens to the total resistance when additional resistors are added in series?
Adding resistors in series increases the total resistance of the circuit.
142
What should you do when adding resistors in parallel?
Add another resistor in parallel with the first.
143
What remains the same when adding resistors in parallel?
The potential difference (pd) is still the same as before.
144
What is the expected trend in resistance when more resistors are added in parallel?
The more resistors you add, the smaller the overall resistance becomes.
145
What type of graph should be plotted to compare results?
A graph of the number of resistors in the circuit against the total resistance.
146
Fill in the blank: Adding resistors in ______ increases the total resistance of the circuit.
[series]
147
Fill in the blank: The more resistors you add in ______, the smaller the overall resistance becomes.
[parallel]
148
What is the first step when investigating how resistance changes with identical resistors in parallel?
Plot a graph of the total resistance of the circuit against the number of resistors.
149
True or False: The resistance of a parallel circuit increases as more resistors are added.
False
