P2 - Sustainable Energy Flashcards
(95 cards)
1
Q
Types of energy stores
- T_____
- K_____
- ______ ______
- E_____
- C______
- N______
- E____________
- E_______
A
Types of energy stores
- Thermal
- Kinetic
- Gravitation potential
- Elastic
- Chemical
- Nuclear
- Electromagnetic
- Electrostatic
2
Q
Thermal energy store - Stores _____ energy
A
Thermal energy stores - Store HEAT energy
3
Q
Kinetic energy store - Energy which an object possesses and stores by being in ______
A
Kinetic energy store - Object that has and stores this type of energy when in motion
4
Q
Gravitational potential energy store - The energy stored by an object _____ up against the force of ________.
A
GPE - Energy stored by an object lifted up against the force of gravity
5
Q
Chemical energy store - Taken in when chemical ____ _____, and given out when _______ _____ are _____.
A
Chemical energy store - Taken in when chemical bonds break, given out when chemical bonds are made
6
Q
Electromagnetic energy stores
___ objects will have energy in this store if they exert a ________ _____ on each other.
A
Electromagnetic energy stores
2 objects will store this energy if they exert a magnetic force on each other
7
Q
Electrostatic energy stores
___ objects will have energy in this store if they exert a _________ _____ on each other.
A
Electrostatic energy stores
2 objects will store this energy if they exert a electrostatic force on each other.
8
Q
Energy is transferred whenever a _______ changes.
A
Energy transferred when a system changes
9
Q
System - Fancy word for a single _____ (e.g. the air in a piston) or a group of _______ (e.g. 2 colliding cars) that you are ________ in.
A
System - Single object or group of objects that you are interested in
10
Q
A system can be changed (and thus energy can be _________) via 2 methods:
- _________
- _________
A
System can be changed - Energy transferred, by…
- Heating
- Working
11
Q
Energy transmission via heating - When energy is transferred from a ______ _____ to a ______ _____.
A
Energy transmission via heating - When energy is transferred from a hotter region to a colder region
12
Q
Energy can be transferred by heating in different ways.
- _________
- _________
A
Energy can be transferred by heating in different ways
- Conduction
- Convection
13
Q
Transferring energy by heating - Conduction
Conduction - Where the _______ _______ of a substance transfer energy to ________ _______.
A
Transferring energy by heating - Conduction
Vibrating particles of substance transfer energy to nearby particles
14
Q
Transferring energy by heating - Convection
Convection - Where the ________ particles of a substance m____ _____ from _______ to ______ regions.
A
Convection - Energetic particles move away from hotter to cooler regions
15
Q
Energy transfer via heating
Energy can also be transferred via _________ (e.g. sound waves).
The energy is often transferred directly to _______ _______ stores.
A
Energy transfer via heating
Energy also transferred via radiation
Energy is often transferred directly to thermal energy stores
16
Q
Energy transfer via WORKING
Work done = ______ t______
A
Work done = Energy transferred
They are the same thing
17
Q
Ways of doing work
- _________
- _________
A
Ways of doing work done
- Mechanically
- Electrically
18
Q
Work done mechanically - An object _______ due to a ____ doing work on it (e.g. pushing, _______ or stretching).
A
Work done mechanically - Object moving due to a force doing work on it (pushing, pulling, stretching etc)
19
Q
Work done electrically - A _____ doing electrical work against __________ (e.g. ______ moving round a circuit)
A
Work done electrically - A charge doing electrical work against resistance (e.g. charge moving round a circuit)
20
Q
Example of work done electrically
A battery-powered heater - energy is transferred _____ from the _______ energy store of the _______ to the ______ energy store of the electric _______.
This energy is then transferred to the _________ by ______.
A
Example of work done electrically
Battery powered heater - Energy transferred electrically from chemical energy store of battery to thermal energy store of electric heater.
This energy then transferred to surroundings via heating
21
Q
Example of work done mechanically
A motor connected to the mains - in a power station, energy is transferred from the _______ energy store of the ____ to the _____ energy store of the water in the boiler.
This is then transferred to the _____ energy stores of the turbines and _______ which produce ________. Energy is transferred by electric ______ (e_______) to the _____ energy store of the ______.
A
Motor connected to mains
Chemical energy store of fuel –> Thermal energy store of water in boiler –> Kinetic energy stores of turbines and generators (which produce electricity)
Energy is transferred by electric current (electrically) to the the kinetic energy store of the motor
22
Q
Working
For battery and _____-operated devices, the electric ______ transfers energy from the _______ energy store of the ____ and does _____ on the device.
A
For battery and mains operated devices - Electric current transfers energy from chemical energy store of fuel and does work on the device
23
Q
Conservation of energy principle
Energy can be ________ usefully, s___, or _______, but can never be ________ or _________.
A
Conservation of energy principle
Energy can be transferred usefully, STORED, or DISSIPATED, but can never be CREATED or DESTROYED
24
Q
Dissipated energy - Sometimes called ______ energy because the energy is being _____ in a way that is not ______ and that you can’t ______.
Eventually, dissipated energy ends up in ______ energy stores
A
Dissipated/Wasted energy = Energy stored in a non-useful way that can’t be accessed
Eventually ends up in thermal energy stores
25
Not all energy is transferred ______ between stores, some if the energy is _______ (usually to the ______ energy stores of the _________).
Not all energy transferred usefully between stores. Some dissipated (usually to the thermal energy stores of the surroundings).
26
Example of wasted energy
A mobile phone is a ______. When you charge the phone, energy is _____ transferred into the system to the ______ energy store of the phone's _______.
BUT, some of the energy is wasted to the _______ energy store of the _______.
Mobile phone is a system
Charge phone - Energy usefully transferred into system to the chemical energy store of battery.
BUT, some energy is wasted to the thermal energy store of the phone
(So, the phone may become hot).
27
Closed systems - Systems where neither _____ nor ______ can _____ or ______.
The net ______ in the total energy of a closed system is always ____.
Closed systems - Systems where neither matter nor energy can enter or leave
Net change in total energy is always 0
28
Example of closed system...
CGP Page 21
29
Power
Power is the ____ of ______ ________ (i.e. how much energy is ________ between ______ per _______.
Power - Rate of energy transfer
| How much energy is transferred between stores per second
30
Domestic electrical appliances usually have ______ _______ - These are their _______ operating _______.
Appliances have power ratings - The maximum operating powers
31
Power
Total energy transferred (work done) for an _______ appliance depends on
- It's ______ ______
- How ____ it has been __ for.
Total energy transferred (work done) on an electrical appliance depends on.
- It's power rating
- How long it has been on for
32
The amount of energy transferred electrically is given by
Energy Transferred (_) = ______ (_) x ______ (_)
E = _ x _
The amount of energy transferred electrically is given by
Energy Transferred (J) = Power (W) x Time (S)
E = P x T
33
Energy transferred but Kwh instead of Joules
Energy Transferred (___) = _____ (__) x ____ (__)
Energy transferred in kWh instead of Joules
Energy Transferred (kWh) = Power (kW) x Time (hours, h)
34
1kWh = _________ J
1kWh = 3,600,000 J
35
Formula for efficiency
Efficiency = ______ energy transferred/_____ energy transferred
Efficiency = Useful energy trans/Total energy trans
Efficiency can be given as a decimal or percentage, doesn't have to be one it can be either unless specified
36
Increasing efficiency - Reduce ______ energy transfers
- Increase efficiency of motor (and other devices) by _________ it
- Make the device more _________
Both of these methods reduce unwanted energy transfers caused by ____ ____ against ________ _____
Increase efficiency - reducing unwanted energy transfers
- Lubricating motors and other devices
- Making devices more streamlined and aerodynamic
Reduces unwanted energy transfers caused by work done against frictional forces.
37
Reducing energy losses in buildings
- Thermal ________ - reduces energy loss by ______- (examples include thick curtains, cavity walls with insulation all reduce _______ and ________)
Double _____ windows and hot water tank _______ reduce _______ and draught _______ reduce ________.
Reducing energy losses in buildings
Thermal insulation - reduce energy loss by heating, thick curtains etc reduce conduction and convection
Double glazed windows + hot water tank jackets reduce conduction.
Draught excludes reduce convection
38
Reducing energy losses in buildings continued
- _______ and ______ conductivity of a walls affects how quickly energy is transferred ____ of a building,
Thicker the walls, _____ the lower rate of energy transfer
Lower the thermal conduct, the lower the rate of energy transfer.
So ____ walls with a ___ thermal conductivity increase the ____ taken for a building to cool down.
Thickness and thermal conduct of walls affect how quickly energy transfers out a building
Thicker walls = Lower rate of energy transfer
Lower thermal conduct = Lower rate of energy transfer
Thick walls + low thermal conduct increase time taken for a building to cool down
39
Sankey diagrams are used to show ________
- The ________ of the arrow represents how much energy is being transferred. The length has NOTHING to do with it.
- Arrow down represents ______/______ energy
Sankey diagrams show efficiency and all energy transfers.
Thickness of arrow represents how much energy is being transferred
Arrow down represents dissipated/wasted energy
Check CGP
40
Non-renewable energy sources - resources that will ___ ___ one day.
Main non-renewable sources on Earth are
- The 3 _____ fuels (____, ___ and ______ ___).
- N_____ fuels (______ and ________)
Non-renewable sources - resources that will run out
Main renewable sources are
- 3 fossil fuels (coal, oil and natural gas)
- Nuclear fuels (uranium and plutonium)
41
Advantages of non-renewable energy sources
- Reliable - Produce lots of ______ from little _______ of fuel (unlike renewable sources)
- Readily _______ - Enough to meet current ______ and can be quickly _______ in order to meet changes in ______. - Non-renewable power stations always have ___ in stock, and can respond ______ to ______ in demand.
Advantages of non-renewable energy sources
- Reliable - Lots of energy from little fuel
- Readily available - Meets current demand, quickly be extracted to meet changes in demand
Power stations always have fuel in stock, can respond quickly to changes in demand
42
Disadvantages of fossil fuels - Damage _______ when in used
- Fossil fuels release ____ when they are ______. CO2 contributes the ________ _____ and ______ ______
- Burning coal and ___ also releases ______ dioxide, which causes ____ ____
Disadvantages of fossil fuels - Damage environment
- Fossil fuels - Release CO2 when burned - ++ greenhouse effect and global warming
- Burning coal and oil - Releases sulphur dioxide - acid rain
43
Disadvantage of using nuclear fuel
- Nuclear wa___ is _______ and difficult to ______ of
- Accidents can be extremely ______ and contaminate _____ areas.
Disadvantage of using nuclear fuel
- Nuclear waste - Dangerous and difficult to dispose
- Accidents can be lethal and contaminate large regions
44
Renewable energy source - resources that will _____ run out.
- Most do some ______ to env, but in less ______ ways than non-renewables.
- Provides less ______ than non-renewables, and ______-dependent ones are ________
Main resources are ______, w____, h______, _____ and ______.
Renewable energy resources - never run out
Does some damage to env, but LESS than non-renews
LESS energy made than non-renews
Weather-dependent ones are UNRELIABLE
Biofuels, wind, hydroelectric, solar and tidal
45
Power stations use _____ to drive a _______.
The set-up costs are _____, but the running costs are ____.
Power stations - Steam to drive turbines - Make electric
High initial setup costs, Low running costs
46
Fossil fuels in power stations to make electricity
1) As the fossil fuel burns, the ______ is ______
2) Water ___ to form ____, which moves and turns a _____
3) Turbine is connected to an _____ _____, which generates a _____ across (and so a ______) through a ___ by spinning a _____ near the ____
4) Current produced by ______ flows through the ______ ___.
Fossil fuels in power stations to make electricity
1) Fossil fuel burns - Heats up water
2) Water boils to form steam - moves and turns turbine
3) Turbine connect to generator, which make p.d. across and current through wire by spinning magnet near wire
4) Current produced by generator flows through national grid
47
Similar setup (boiling water to make _____ in order to turn ______ etc) is also used in other types of generation.
- Nuclear power - Energy from nuclear ______ is used to ____ the water.
- In hydroelectric, ____ and ____, turbine is turned _____ without the need to ___ water and make _____.
Similar setup - boil water, make steam, turn turbine) also used for other types of generation
- Nuclear power - Nuclear fission heats water
- Hydroelectric, wind, tidal - turbine turned directly, no water need to be heated to make steam
48
Wind power
- Each wind turbine has a _______ inside of it. The rotating ____ turn the ______ to produce
Wind power
Each turbine has a generator inside of it. The rotating blades turn the generator to produce electricity
49
Characteristics of wind power
- ____ set-up costs, but no ____ costs
- No _______ (except a little when they are ____)
- Only work when it's _____, so can't always ______ electricity, or respond to ___ _______.
- Some people think they look ____ are are very _____.
However, they can be placed ______ which generates ____ energy.
Characteristics of wind power
- High set-up costs, no fuel cost
- No pollution (except little when made)
- Only work when windy, electricity not always produced, can't respond to high demand
- Look ugly and very noisy
Placed offshore to generate more energy
50
Solar Cells
- Often used in ______ places where there is not much choice (e.g. Australian desert) and to power electric road ____ and _______.
Solar cells
- Used in remote places where there is no choice,
also to power electric road signs and satellites
51
Solar Cells characteristics
- High initial ___-__ costs, but after energy is ____ and running costs are almost ___.
- No ______ when in use(but use lots of _____ to make)
- Mostly used on a ______ scale. (e.g. homes)
- Best in _____ countries, but can be used in ______ ones as well.
- Can't produce electricity at _____ and can't increase _______ when in extra _______.
Solar Cells characteristics
- High set up costs, free energy, almost 0 running costs
- No pollution when in use (lots of energy to make them tho)
- Small scale use (e.g. homes)
- Best in sunny countries, but can be used in cloudy ones
- No electricity at night, no increase in production to meet extra demand
52
Biofuels - Made from many different things - farm ____, animal _______, ______ rubbish to specifically grown ____.
_____ to produce electricity or to run ___ in the same way as fossil fuels.
Renewable because we can just ____ ____.
Biofuels - made from lots of stuff - farm waste, animal droppings, landfill rubbish, specifically grown crops (e.g. sugar canes).
Burnt to produce electricity or run cars like fossil fuels
Renewable coz we can just grow more
53
Biofuels continued
- Burning them releases ____, but the ____ you grow (either to burn or as animal ____) _____ CO2 from the atmosphere (so there's no __ ____ in the atmosphere)
Biofuels
Burning them releases CO2, plants grown as fuel or animal feed REMOVE CO2, so no NET CHANGE in the atmosphere
54
Biofuels characteristics
- Fairly _____ as they can be ______ fairly quickly and easily. But harder to respond to _______ _____ demands as crops take ____ to ____ (but you can ______ biofuels to combat this)
- ____ cost to make biofuels, ____ for growing biofuels could lead to shortages of _____ or _____ to grow enough ____ for food for everyone
- Land and _______ have been _____, so species are left to _____. _____ and burning of vegetation also increases ____ and _______
Biofuel characteristics
- Fairly reliable - generated fairly quickly and easily - Hard to respond to immediate energy demands - crops take long to grow - stockpiling crops prevents this
- High cost to make them, Land use for growing biofuels can lead to shortages of water or space to grow enough crops and food for everyone
- Land cleared, habitats destroyed, animals suffer, decay and burning vegetation - increases CO2 and methane emissions
55
Hydroelectricity
- Involves ______ a v____ by building a big ___.
- Water is ____ and allowed out through ______.
Hydroelectricity
Involves flooding a valley by building a big dam
Water is stored and allowed out through turbines
56
Hydroelectricity characteristics
- Big impact on _______, ______ of valley leads to possible loss of _______ for some ______
- Advantage - _______ response to increase electricity demand - more _____ can be let out through the _____ to generate more _______.
- ____ initial setup costs, but ______ running costs and it's a ______ energy source.
Hydroelectricity characteristics
- Environment - Flooding valley - Loss of habitats for some species :(
- Advantage - Immediate response to increase production - More water let out through turbine to make more electricity
- High setup costs, minimal running costs, reliable source
57
Tidal barrages - Big ___ built across river ______ with ______ in them.
They use the ___ and moon's ________.
As the tide comes in, it ___ ___ the e_____. The water is then let out through ______ at a set _____.
Tidal barrages - Big dams built across river estuaries with turbines in them
Use sun and moon's gravity
Tide comes in --> fills estuary. Water let out through turbines at a set speed.
58
Tidal barrages characteristics
- No ______ but affect ____ access, can spoil the ___ and they alter the _______ for w____
- Pretty ______ (always happen ____ a day). But the height ____ and tidal barrages don't work when the water ______ is the ____ on either ____.
- Can only be used in ____ estuaries.
Tidal barrages characteristics
- No pollution but affect boat access, spoil views and alter habitats for wildlife
- Pretty reliable (tides occur twice a day). But height varies - barrages don't work when water is the same level on either side
- Can only be used in some estuaries
59
Deciding which energy source to use
There are ___, drawbacks and ______ that need to be _____ when deciding the ____ energy resource to use
Categories to consider when evaluating are
- _______ and abundance of the resource
- C___
- How _______ they produce ______
- _________ impact
- _________ (e.g. jobs) they create.
Deciding which energy source to use
Risks, drawbacks and benefits need to be evaluated to decide the best energy resource to use
Categories to consider when evaluating are
- Availability and abundance of resource
- Cost
- How reliably they produce energy
- Environmental impact
- Opportunities (e.g. jobs) they create
60
Decisions of energy resource depend on the circumstance - Hydroelectric
- Hydroelectric power is great, ______ and relatively ________-friendly, but if there's nowhere suitable to _____ a hydroelectric ______ _____, then Hydroelectric cannot be ______.
Similarly, the ___ cost of building the ______ _______ may be off-putting - even if some people think it's _____ the money.
Decisions of energy resource depend on the circumstance - Hydroelectric
Hydroelectric, great reliable and env friendly. No suitable place to make power station, then can't be used
Also, high cost of building power plant is off-putting, even if people think it's worth the money
61
Decisions of energy resource depend on the circumstance - Nuclear
- Nuclear fuel is good, ____ and re____ energy resource to use. _______ up and ______ down a nuclear power station provide many ____ but is ______ and _____.
Also the risk of a major _________, which can cause lots of _____ - some say the benefits _______ the risks whilst others say the potential ______ isn't worth it.
Decisions of energy resource depend on the circumstance - Nuclear
- Nuclear is good, clean and reliable. Setting up and shutting down a nuke power station provide many jobs - BUT is difficult and expensive
- Risk of major catastrophe - some say benefits>risks whilst others say the potential damage is not worth it
62
Energy demands are changing
- World demand for energy is continually _______ due to population ________, _______ advances (e.g. rise of computers and electronic devices) and our _______.
Energy demands are changing
- World demand for energy continually increasing - population increase, technological advances and our lifestyles
63
Sustainable energy resources are those that we can keep on using in the ____ ____.
Renewable resources tend to be ________ as they won't ___ ___ and aren't usually too _______ to the environment.
Sustainable energy resources - We can keep using in the long term
Renewable resources are sustainable - won't run out, not too damaging to environment
64
Energy demands are changing
Concerns about sustainability have led people to make ______ in their everyday ___ to put ______ on their ________ in order to cause national ______. This has led to countries creating _______ for using _______ resources, which in turn puts pressure on other _______ to do the same.
Energy demands are changing
Concerns on sustainability - Changes to everyday lives - Put pressure on governments to make national change - Countries make targets for using renewable resources - puts pressure on other countries to do the same
65
Energy demands are changing
Research is being done to find ____ energy resources, and looking at ________ existing ones. The research into and ________ of new energy provides ____, as does the building of new _______ ______.
Energy demands are changing
Research being done - new energy resources - improving existing ones. Research into and development of new energy provides jobs, so does building new power plants
66
Energy demands are changing
These factors have all led to an _______ in the use of _______ energy resources
- In the UK we generate some electricity from _____ ___. They're also used for _______ and ______. as they're relatively _____, _______ and reliable.
But, we can't keep using them ____ term - they're not _______. So slowly, the UK is trying to _______ the use of more _______ energy resources.
Energy demands are changing
These factors - increase in use renewable energy resources
- UK, some electricity generated from fossil fuels - Fossil fuels also used for heating and transport - relatively cheap, efficient and reliable.
Can't keep using them long term - not sustainable. - Slowly UK trying to use more sustainable energy resources
67
New energy resources may also bring with them new ________ and ________ challenges as well as b____.
E.g., nuclear energy was first used to generate electricity in the ______. It took a long time to _______ the technology to release _______ from nuclear ____ using a nuclear ______. Took even longer to develop the technology to _____ and ______ the nuclear reactions to make it safe enough to generate _______.
Even though now it is relatively ____ and reliable, it still generates radioactive ____ which is highly _____ for a very long ___. This could greatly damage the _______ if not _____ and stored correctly - an unforeseen ______ when nuclear fuel was first introduced.
New energy resources bring new technological and environmental challenges as well as benefits
Nuclear - 1950s, long time to develop technology to release energy from nuclear fuels using a nuclear reaction. Even longer to develop the technology to house and control the nuclear reaction to make it safe enough to generate electricity
- Relatively safe and reliable now, still generates radioactive waste - highly toxic very long time - damage the env if not treated and stored correctly - unforeseen challenge when first introduced.
68
National grid - A giant web of ____ and ________ that covers the UK and connects ______ _____ to _______.
National grid - Giant web of wires and transformers that covers the UK and connects power stations to consumers
69
The national grid transfers energy _______ from ______ _____ anywhere on the grid (the _____) to anywhere else on the grid where it is ______ (the _____) e.g. homes and ________.
National grid transfers energy electrically from power stations anywhere on the grid (supply) to anywhere else on the grid where it is needed (demand) e.g. homes and industry
70
Transformers are used to increase the generated electricity to a very h___ ___ before it is _______ through the network of the national grid.
Transformers - Increase generated electricity to a very high P.D. before transmitted through national grid
71
Transferring electrical power at a very high ___ helps to reduce ______ _____.
The P.D. is then _______ by another transformer to a level that is ____ for use before being supplied to homes and ________.
Transferring at very high P.D. - reduces energy losses.
| P.D. is then reduced
72
Move power round the national grid
Before electrical power leaves the ____ station - it is transferred at high ____ using ____-__ ________ to increase the P.D. from ________V or ________V
Before electrical power leaves the power station - Transferred at high P.D. using STEP-UP transformers to increase P.D. to 275,000V or 400,000V
73
Move power round the national grid
After, before electrical power enters homes and factories, the P.D. is _______ by ___-___ _______ to _____V (large factories), ______V (medium factories), ____V (homes, shops, small factories and offices)
After, before electrical power enters home and factories, P.D. is decreased by STEP-DOWN transformers to
- 33,000V (Large factories)
- 11,000V (Small factories)
- 230V (Homes, shops, small factories and offices)
74
The transfer of electrical energy via the grid is very ______. When currents is higher in a cable, more energy is _______ to the surroundings through ______. As ___ currents waste more energy than ___ currents, electrical power is transported around the grid at a ____ voltage and a ___ current.
Transfer of electrical energy via grid - very efficient
Higher current in cables - More energy dissipated to surroundings via heating
High currents waste more energy than low currents
High voltage, Low current is used to transport electricity
75
Transformers - Device that can change the ______ of an _______ current (___).
A basic transformer is made from two ____ of ___ - a pr_____ coil from the ac ____ and a ______ coil leading to the ac ______.
Transformers - Devices that can change the voltage of an alternating current (a.c.)
A basic transformer is made from two coils of wire - primary coil from ac input, secondary coil leading to ac output.
76
Step-up transformers - used to ______ voltages. Used when electrical power _____ at the power station is stepped up from ______V to _______V or _______V for transportation around the UK.
Has more ____ of wire on its ________ coil than it does on the ______ coil.
Transformers only work with an ___ input. This transformer increases voltage by _______ the current.
Step-up transformers - Increase power output at power station from 25,000V to 275,000V or 400,000V
More turns of wire on secondary coil than primary coil
Only work with a.c. input. Increase voltage by decreasing current (yes this is true don't question it).
77
Step-down transformers - used to ______ voltages. Used when voltages need to be lowered for ____ and ______.
Has more ____ of wire on the _________ coil than it does on the _________ coil.
This transformer decreases voltage by _______ current
Step-down transformers - decrease voltages - Used when voltage needs to be lowered for homes and businesses
More turns of wire on primary coil than secondary coil
Decreases voltage by increasing current.
78
Mains supply is ___, Battery supply is ____.
Mains supply - A.C. Battery Supply D.C.
79
In A.C. supplies the current is constantly changing ______. They are produced by _______ ______ in which the ______ and _______ ends of the p.d. keep ________.
A.C. - current constantly changing directions. Produced by alternating voltages - positive and negative ends of the p.d. keep alternating
80
UK domestic (____) supply (the electricity in your ____) is an ___ supply at ____V with a frequency of _____.
```
UK domestic (mains) supply - electricity at home.
A.C. 230V 50Hz supply
```
81
Cells and batteries supply ____ current.
D.C. is a current that always flows in the same _______. It's created by _____ ______. This voltage is usually smoothed out to provide a ______ line on a graph of P.D. against ____. (Check CGP for graphs)
Cells and batteries supply D.C. current
D.C. current always flows in the same direction - Created by direct voltage. This voltage is smoothed out to provide a straight line on a graph of P.D. against time
82
Plugs contain three wires
- L___ wire - _____
- N____ wire - _____
- _____ wire - ____ and ______
Plugs contain three wires
- Live wire - Brown
- Neutral wire - Blue
- Earth wire - Green and yellow
83
Live wire - _______
The live wire carries the ___. It al_____ between a high ________ and ________ ___ of about ____V.
Live wire - Brown
- Carries the P.D. Alternates between a high positive and negative P.D. of about 230V
84
Neutral wire - _____
The neutral wire ______ the circuit - when the appliance is operating normally, current flows through the ___ and ______ wires. It is around ___V
Neutral wire - Blue
- Completes the circuit. Current flows though live and neutral wires. Neutral wire - around 0V
85
Earth wire - _____ and _____
The earth wire is for _______. It carries the current ____ if something goes ____. It's also at ___V.
Earth wire - Green and Yellow
- For safety, carries current away if something goes wrong. Earth wire - at 0V as well
86
The P.D. between the live wire and the _____ wire equals the ______ P.D. (____V for the mains)
P.D. between live and neutral wire = Supply P.D. (230V for the mains)
87
The P.D. between the live wire and earth wire is also ____V for a ____-connected appliance
P.D. between live and earth wire also equal to 230V for a mains-connected appliance
88
There is no P.D. between the ______ wire and the _____ wire - they're both at ___V
No P.D. between neutral and earth wire - Both 0V
89
Your body is an example of an ______ conductor, and is also at ___V. This means if you touched a li__ wire, there'd be a _____ ___ across your body and a ______ will flow through you. This large electric shock can _____ or even ____ you.
Body - Earthed conductor - 0V. Touch live ire, large P.D. across body, current flow through body. - Large electric shock can injure and kill you.
90
Even if a plug socket is off there is still a risk that you could get an ______ ____. A ______ isn't flowing but there is still a ___ in the live part of the socket, so your body could provide a ___ between the ______ and the ______ if you made _______ with it.
Even if plug socket is off - still risk of electric shock. Current isn't flowing but P.D. is still in the live part of the socket - so body can provide a link between the supply and the earth if you made contact with it.
91
The 3 safety features in plugs and appliances are
- _____
- ________ ______
- _____ wire
The 3 safety features in plugs and appliances are
- Fuses
- Double insulation
- Earth wire
92
The fuse - a fuse is designed to ___ if a current flows through it that is too _____.
For example, if a fuse has a rating of 3 A then it will melt if the current flowing through it exceeds __ A.
This is because if the current gets too high, too much ____ could be produced which would cause the appliance to catch ___. Once the fuse melts, the circuit is ______ and no current can ____.
Fuse - melts when too large of a current flows.
3A fuse will melt when current>3A
Melts coz if current too high, too much heat made so appliance will catch fire.
Fuse melts --> circuit broken --> no current can flow
93
Double insulation ‐ devices which contain ____ parts are surrounded with a ______ that is made from a _____ insulation. This stops the user from coming into _____ with any of the metal parts that ______ current. Coming into contact with these areas could cause _______.
Double insulation - metal parts surrounding by casing made from a plastic insulation. - Stops user coming into contact with metal parts that conduct current.
Coming into contact can cause electrocuation.
94
The earth wire - this is designed so that a large current passes through the ____ in the event of the live wire _______ and touching a _____ part of the appliance. If there were no earth wire, and a live wire were to loosen and touch a metal part of the appliance, someone touching the appliance would be _______, as a large current would pass through the _____ to the ground (______).
Earth wire - Diverts large current away via the fuse when live wire loosens and touches metal part of appliance. No earth wire, live wire make contact with metal, person gets electrocuted, large current pass through body to the ground (Earth).
95
Check CGP and Bitesize to refresh and go over this.
Affirmative
