Energy And Electricity Flashcards
1
Q
What is energy stored in
A
Systems.
2
Q
Energy stores and systems - what is a system
A
An object or a group of objects
3
Q
What are the 8 energy stores?
A
Chemical, kinetic, elastic potential, gravitational potential, thermal, magnetic, electrostatic, nuclear.
4
Q
Give the energy store that increases and decreases in this scenario:
An object thrown upwards.
A
Increases: grav potential
Decreases: kinetic
5
Q
Give the energy store that increases and decreases in this scenario:
A moving object hitting a wall
A
Increases: thermal
Decreases: kinetic
6
Q
Give the energy store that increases and decreases in this scenario:
A bow releasing am arrow
A
Increases: kinetic
Decreases: Elastic potential
7
Q
Give the energy store that increases and decreases in this scenario:
A vehicle slowing down when breaking
A
Increases: thermal (caused by friction)
Decreases: kinetic
8
Q
Give the energy store that increases and decreases in this scenario:
Heating water on a camping stove
A
Increases: thermal
Decreases: chemical (in gas)
9
Q
Give the energy store that increases and decreases in this scenario:
Using a battery operated fan
A
Increases: kinetic and thermal (of the motor)
Decreases: chemical (in battery)
10
Q
Energy stored and systems- how can systems be changed? (3 things)
A
- Heating
- Work done by forces
- Work done when current flows.
11
Q
A fully charged electric scooter is ridden down a street at a constant speed.
Explain how the energy stored change in this system.
A
Chemical energy stored under the battery is transferred to the kinetic energy store of the scooter abs then to the thermal energy store of the surroundings due to air resistance and friction between the ground and the wheels.
12
Q
What is chemical energy
A
The energy stored in chemical bonds
13
Q
What is kinetic (movement) energy
A
The store of energy of a moving object
14
Q
What is elastic potential energy
A
the energy that is stored in an object when it is stretched or compressed.
15
Q
What is gravitational potential energy
A
the energy stored in an object due to its height, or vertical position from the zero position, usually the surface of the Earth
16
Q
What is thermal (heat) energy
A
the energy contained within a system that is responsible for its temperature
17
Q
What is magnetic energy
A
Energy created by the strength of a magnetic field
18
Q
What is electrostatic energy
A
The energy stored when repelling charges have been moved closer together or when attracting charges have been pulled further apart
19
Q
What is nuclear energy
A
The energy stored in the nucleus of an atom
20
Q
What is the symbol of kinetic energy and what are the units?
A
Symbol - E (with a small k in the bottom corner next to)
Units - Joules (J)
21
Q
What is the symbol and units for mass
A
Symbol - m
Units - Kilograms (kg)
22
Q
What is the symbol and units for velocity (speed)?
A
Symbol - v
Units - meters per second (m/s)
23
Q
What are the units and symbol for elastic potential energy
A
Symbol - E (with a small e next to it in the bottom corner)
Units - Joules (J)
24
Q
What are the units and symbol for spring constanst?
A
Symbol - k
Units - newtons per meter (N/m)
25
What ate the symbol and units for extension?
Symbol - e
Units - meters (m)
26
Springs also have a store of elastic potential energy if it's squashed. The amount of energy can be calculated using the equation for elastic potential energy, but what is replaced with extension?
Compression
27
What is the limit of proportionality and whay can't you do?
The point at which an object will no longer return to its original shape or length when stretched or squashed.
You can't calculate the elastic potential energy
28
What is gravitational potential energy (g.p.e) measured in and what's the symbol?
Symbol - E (with a small p)
Units - Joules (J)
29
What is gravitational friend strength measured in and what is the symbol?
Symbol - g
Units - Newtons per kilogram (N/kg)
30
What is height measured in and what is the symbol
Symbol - h
Units - meters (m)
31
What is the G.P.E. of earth
9.8N
32
Can height also be the change in vertical height?
Yes.
33
What is specific heat capacity?
The specific heat capacity of a substance is the amount of energy needed to increase the temperature of one kilogram (1kg) of a substance by one degree Celcius (°C)
34
The amount of thermal energy needed to increase the temperature of a substance depends on its..
Mass and specific heat capacity.
35
What are the symbol and units of change in thermal energy
Symbol - (triangle)E
Units - Joules (J)
36
What are he units and symbol for specific heat capacity
Symbol - c
Units - Joules per kilogram per degrees Celsius (J/kg°C)
37
What is the units and symbol for temperature change
Symbol - (triangle)(theta)
Units - degrees Celsius (°C)
38
What is power?
The rate at which energy is transferred or the rate at which work is done in any given amount of time.
39
Is Energy Transferred and Work Done the same?
Yes.
40
What is the symbol and units for Power.
Symbol- P
Units - watts (W)
41
What is the symbol and units for work done?
Symbol- W (italicised)
Units - Joules (J)
42
What is the symbol and units for energy transferred?
Symbol- E
Units - Joules (J)
43
What is the symbol and units for time
Symbol- t
Unit - seconds (s)
44
What is 1 Watt equal to?
1 Joule per second
45
In what ways can energy be transferred?
Usefully and wasted (dissipated)
46
What is a closed system?
A system that does not allow transfer of matter in or out of the system. This means that no energy is dissipated or wasted from the system and the total amount of energy in the system is constant.
47
How can friction be reduced?
By lubricating the moving parts of machinery with oils and powders.
48
When an electrical current flows through a resistor, energy in the chemical store of a battery is transferred to the what store of energy of the surroundings by electrical work?
Thermal
49
Do metals with a high or low thermal conductivity have a higher rate of energy transfer by condition across the material?
High thermal conductivity
50
Are materials with low thermal conductivity are good or bad insulators and why?
Good insulators because they transfer energy more slowly and therefore release less thermal energy.
51
What is efficiency?
How much of the total energy transferred is transferred to useful energy stored and how much is transferred to less useful stores or wasted.
52
After calculating efficiency, how is it written as?
A decimal (between 0.1 and 1.0) or as a percentage (decimal x 100).
53
True or false.
Efficiency has units.
False.
54
What is Power?
The rate at which energy is transferred in Watts.
55
What is non-renweable energy
Energy resources that are being used up faster than they can form. It has a finite supply.
56
What causes energy sources to become non-renewable (finite)?
They form very slowly or it is no longer being formed.
57
What are renewable energy sources
Energy sources that can be replenished as its being used, either by human action or naturally
58
Which fossil fuel contributes to global warming
Carbon dioxide.
59
What are the environmental risks of using hydroelectric power
Risk flooding, damages land/habitats.
60
What are the environmental risks of using tidal power
Damage to marine habitats
61
What are the environmental risks of using wave power
Has low impact
62
What are the (2) non renewable energy sources?
Fossil fuels (Oil, Gas, Coal)
Nuclear
63
What are the (7) renewable energy sources
Biofuel
Geothermal
Hydroelectric
Sun
Tides
Water waves
Wind
64
What are the advantages (3) and disadvantages (2) of fossil fuels?
ADVANTAGE: relatively low costs, easy to use, very adaptable.
DISADVANTAGES: produce carbon dioxide (global warming) and sulfur dioxide (causes acid rain and can cause breathing problems) and are finite.
65
What are the advantages (1) and disadvantages (3) of nuclear power?
ADVANTAGES: no greenhouse gases are produced, a large amount of energy is produced from a small amount of fuel.
DISADVANTAGES: disposal of uranium is costly and hazardous, huge costs to build, run and decommission power stations, risk of catastrophic accidents.
66
What are the advantages (2) and disadvantages (1) of biofuel?
ADVANTAGE: can use up plant and animal waste, replacement engine fuel for transport.
DISADVANTAGES: some biofuels are grown especially which uses a lot of land thy could be used for food production.
67
What are the advantages (2) and disadvantages (2) of geothermal?
ADVANTAGS: Can be used for heating local areas, and electricity can be generated for hot rocks.
DISADVANTAGES: not available everywhere and sometimes in dangerous and inaccessible areas.
68
What are the advantages (2) and disadvantages (1) of hydroelectricity?
ADVANTAGE: available at any time, can be stopped and started at any time.
DISADVANTAGES: areas of natural beauty can be flooded to make dams and reservoirs required.
69
What are the advantages (3) and disadvantages (3) of sun energy?
ADVANTAGES: Solar cells on rooftops and solar farms generate electricity, also used to heat water, in development.
DISADVANTAGES: not available at night, works better in places with more intense sun, visual impact on landscape.
70
What are the advantages (1) and disadvantages (2) of tidal energy?
ADVANTAGE: electricity can be generated at predictable times.
DISADVANTAGES: could damage marine habitats, expensive, few suitable places for barrages.
71
What are the advantages (1) and disadvantages (3) of water wave energy)
ADVANTAGE: can generate electricity on a small scale
DISADVANTAGES: maintenance, impact on marine habitats, inconvenience to shipping.
72
What are the advantages (3) and disadvantages (3) of wind energy?
ADVANTAGES: more suitable offshore sites in the UK, low maintenance when established, turbines can be built out at sea.
DISADVANTAGES: Unreliable unless wind speed is within the right range, visual pollution of turbines on land, many turbines are needed to generate suitable amounts of electricity.
73
What is the function of an open switch
Creates a gap in the circuit so electricity can't flow around the circuit.
74
What is the function of a closed switch
Allows the current to pass through, completing the circuit.
75
What is the function of a lamp (circuit)?
Produces light
76
What is the function of a fuse
Protect the electrical equipment from excessive current to oreveht short circuits.
77
What is the function of a cell
Converts stored chemical energy into electric energy, allowing positive charges to flow from the positive terminal to the negative one.
78
What is the function of a voltmeter
Measures electric potential difference
79
What is the function of a battery (circuit)
Provides a voltage which allows the current to flow through
80
What is the function of a ammeter
Measures the current and voltage
81
What is the function of a diode
Allows electric current to flow in one direction, while blocking it from going in the opposite direction.
82
What is the function of a thermistor
Used as temperature sensors.
83
What is the function of a resistor
Limits or regulates the flow of electrical current.
84
What is the function of a variable resistor
Controls the flow of electrical current by changing its resistance
85
What is the function of an LRD
Detects light levels
86
What is the function of a LED
Transform electrical energy into light energy
87
What is an electric current
The rate of flow of electrical charge
88
What circuit component measures electrical current
Ammeter
89
The rate of flow of ___ , or ____ of the ___can be measured by determung how much ___charge passes by a point in the circuit each ___.
1. Charge.
2. Size
3. Current
4. Charge
5. Second
90
What carries the electrical charge
Electrons
91
What are the symbols and units dor charge flow
Symbol: Q
Unit: coulombs (C)
92
What is the symbol and unit for current
Symbol: I
Unit: amperes [amps] (A)
93
What is the symbol and unit for time
Symbol: t
Unit: seconds (s)
94
Complete the sentence:
One coulomb is the ___ that passes at a point in the circuit when there is a ____ of one ampere for one second.
1. Charge
2. Current
95
What is resistance
A measure of how hard it is for the charge to flow through a component or material.
96
Complete the sentence:
The current in a component depends on the ____ ____ across the component and the ___ of the component.
1. Potential difference
2. Resistance
97
Complete the sentence:
For a given ____ ___, the current ___ as the ___ increases.
1. Potential difference
2. Decreases
3. Increases
98
Complete the sentence:
The ___ the resistance of the component, the ___ the ___ for a given ___ ___ across the component.
1. Greater
2. Smaller
3 current
4. Potential difference
99
What is potential difference also knows as
Voltage
100
What is the symbol and unit for potential difference
Symbol: *V*
Unit: volts (V)
101
What is the symbol and unit for resistance
Symbol: *R*
Unit: ohms (Omega symbol)
102
Explain why the resistance in a wore changes as the wire gets hotter
As the wire gets hotter, the atomic vibrations are larger so electrons collide with atoms more frequently and the resistance increases.
103
104
What resistors are ohmic conductors?
When the value of R (resistance) remains constant as the current changes.
105
What is a non ohmic conductor?
When the value of R (resistance) changes as the current changes.
106
Give examples of non-ohmic conductors. (4)
1. Lamps
2. LDRs
3. Diodes
4. Thermistors
107
In ohmic conductors, at a constant temperature, how do you describe the current and potential difference?
Directly proportional
108
Describe the relationship between the temperature and a filament lamp (resistors - current and potential difference)
The resistance of a filament lamp increases as the temperature of the filament increases
109
Describe the relationship between the current and a diode (resistors - current and potential difference)
The current through a diode flows in only one direction.
The diode has such a high resistance in the reverse direction that no current can go that way.
110
Describe the relationship between the temperature and a thermistor (resistors - current and potential difference)
The resistance of a thermistor decreases as the temperature increases
111
Describe the relationship between the light intensity and a LDR (resistors - current and potential difference)
The resistance of an LDR decreases as the light intensity increases.
The resistance of an LDR is low so more current can flow through.
112
What is a series circuit
A single continuous loop
113
What is a parallel circuit
A circuit with components that aew connected across each other.
114
Describe the total potential difference in a series circuit
The total potential difference of the power supply is shared between the lamps
115
Describe the total potential difference in a parallel circuit
The potential difference across each lamp is the same
116
Describe the current in a series circuit
The current is the same through each lamp
117
Describe the current in a parallel circuit.
The total current through the whole circuit is the sum of the current through each lamp.
118
Describe the resistance in a series circuit.
Total resistance is the sum of the resistance of each lamp. The current passes through all the resistors in series so adding resistors decreases the current and increases the total resistance
119
Describe the resistance in a parallel circuit.
The total resistance is less than the resistance of the bulb with the smallest resistance in the circuit. The resistance splits between the resistors in parallel.
120
Describe the lamps in a series circuit
The lamps are both on or off
121
Describe the lamps in a parallel circuit
The lamps can be switched on or off separately.
122
What is a direct current
The current is always in the same direction
123
What is an alternating current
The direction of the current is constantly changing.
124
Describe a potential difference-time graph for a direct current voltage
The graph shows a straight line at a constant potential difference
125
Describe a potential difference-time graph for an alternating current voltage
The graph shows a curve alternating between positive and negative potential differences. The positive and negative values indicate the direction of the current.
126
Give two examples of devices in the same home that use a d.c. supply.
Phone, remote control
127
What colour is the earth wire
Yellow and green stripes
128
What is the colour of the live wire
Red-Brown
129
What is the colour of the neutral wire
Blue
130
What potential difference with the earth does the earth wire have?
0 V
131
What potential difference with the earth does the live wire have?
About 230 V
132
What potential difference with the earth does the neutral wire have?
At or close too 0 V
133
What are the purposes of the earth wire. (2)
Safety wire
Only carries a current if there's a fault.
134
What are the purposes of the live wire? (2)
Carries the alternating p.d from the power supply
Connects to the fuse
135
What are the purposes of the neutral wire? (1)
Completes the circuit.
136
Explain why different coloured insulation is used in a three-core cable?
To identify different wires and to connect wires for safety.
137
Describe 2 dangers of using mains power supply
Electric shock from contact with a live connection. Fire can be caused by too much current.
138
How do you identify d.c. supplies?
They are devices that use a battery/ use batteries.
139
What are the 6 components of a mains plug
Neutral wire, live wire, earth wire, fuse, cable grip, outer insulation
140
What happens if a person touches a live wire or live appliance
They will get an electric shock
141
What is the symbol and units for power?
Symbol: *P*
Unit: watts (W)
142
What is energy transferred equal too when working out power
Work done.
143
What is 1kW in Watts
1000 W
144
An electrical appliance transfers more energy if it: (2)
1. Has a higher power rating
2. Is switched on for more time
145
The energy is usually transferred: (2)
1. To make electric motors move (kinetic energy)
2. For use in heating (thermal energy)
146
When a charge flows, what is energy transferred by?
Electrical work
147
Give one example of a device that transfers useful energy by electrical work to:
a) kinetic energy
b) thermal energy
a) any electrical device with a spinning motor. E.g. washing machine
b) any electrical device designed to get hot. E.g. iron.
148
What is the national grid
The system of cables and transformers that links power stations to consumers.
149
What are step-up transformers used for in the national grid
They are used to increase the potential difference from the power station.
150
What are step-down transformers used for in the national grid?
They are used to decrease the potential difference from the transmission cables for use in homes.
