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DT theory GCSE > November test Weeks 6-10 > Flashcards

November test Weeks 6-10 Flashcards

1
Q

how is electricity produced (generally)

A
  • involves rotating a turbine which turns a generator
  • fossil fuels burned to create heat to superheat the water
  • steam turns turbine (linked to generator) to produce electricity
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2
Q

Fossil fuels advantages

A
  • cheap and reliable (does not rely on weather)
  • well developed systems to harness energy
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3
Q

Fossil fuels disadvantages

A
  • contains high levels of carbon and contributes to global warming
  • non-renewable and unsustainable
  • accidents could occur to add to pollution and environmental contamination
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4
Q

What are fossil fuels

A
  • finite resources
  • gas -> electricity in the UK, heating and cooking
  • coal -> burned to create energy
  • oil -> create plastics or fuel
  • burning these fuels produces large amounts of CO2 (climate change)
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5
Q

What is shale gas?

A
  • a natural gas trapped in the earth’s crust
  • fracking: process to release gas from shale
  • sends a high pressure mixture of water, sand, chemicals into the rock to release gas
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6
Q

Why is fracking controversial?

A
  • fractures rock to release gas -> causes earth tremors that damage building foundations
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7
Q

What is nuclear power?

A
  • produces energy by fission (splitting uranium atoms in a nuclear reactor)
  • same heat/steam/turbine process as coal power station except heat is made with nuclear fission
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8
Q

Advantages of nuclear power

A
  • no need for a large amount of space to generate electricity
  • does not produce CO2 or contribute to global warming
  • reliable (not dependant on weather)
  • low volume of waste produced
  • reduces demand for finite resources
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9
Q

Disadvantages of nuclear power

A
  • risk of nuclear accidents
  • disposal of nuclear waste (expensive), takes a long time to decay
  • high levels of security of needed (terrorism)
  • decommissioning nuclear plants safely-> costly (high risk of contamination)
  • construction, operation and decommissioning nuclear power plant may harm the environment
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10
Q

what is renewable energy?

A

Natural sources of energy that are non-finite and can be quickly replenished (eg. wind, biomass, solar)

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11
Q

What is wind power?

A

energy from wind turns propeller-like blades on rotor (connected to generator)

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12
Q

Advantages of wind power

A
  • cost effective
  • clean source of energy
  • sustianable and renewable
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13
Q

Disadvantages of wind power

A
  • unpredictable (weather based)
  • can be noisy
  • affect visual appearance of landscape
  • distance from wind sites (location on hilltops or out at sea) = high costs to connect to national grid
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14
Q

what is tidal power?

A
  • movement of water (tide) turn underwater turbines which drive the generators
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15
Q

Advantages of tidal power

A
  • predictable
  • renewable
  • clean source of energy
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16
Q

Disadvantages of tidal power

A
  • expensive to set up and maintain
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17
Q

How do solar panels create energy

A
  • abosorb light into photovoltaic cells which is converted into electricity
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18
Q

Advantages of solar panels

A
  • renewable
  • clean
  • energy can be collected on sunny or cloudy days
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19
Q

Disadvantages of solar panels

A
  • low energy generated during winter months (daylight hours are shorter)
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20
Q

What is biomass and how is it used?

A
  • produced from organic matter
  • energy extracted by burning/ anaerobic digestion (no air, bacteria breaks down organic matter and produces methane)
  • methane can be used to heat homes or fuel
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21
Q

Advantages of biomass

A
  • renewable
  • carbon neutral
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22
Q

Disadvantages of biomass

A
  • risk of deforestation if trees are not planted
  • CO2 emissions are made (global warming)
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23
Q

What is hydroelectric power?

A
  • turbine converts kinetic energy of falling water into mechanical energy and generator turns it into electricity
  • eg. dams
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24
Q

Advantages of hydroelectric power

A
  • renewable
  • reliable
  • clean
  • regulated according to demand (can be switched on and off)
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25
Q

Disadvantages of hydroelectric power

A
  • cost and environmental pollution of building dam is high (CO2 produced when building)
  • impacts on surrounding water flow
  • affects ecosystems
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26
Q

How is kinetic energy stored?

A
  • using kinetic pumped storage systems
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27
Q

How do kinetic pumped storage systems work?

A
  • holds water in upper reservoir
  • high electricity demand = dam opens and water released into lower reservoir to drive turbines -> electricity
  • night (lower electricty demand) water is pumped back up & cycle continues
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28
Q

How do batteries (portable energy storage systems) work

A
  • contains electro-chemicals that react with each other to produce an electric voltage
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29
Q

Describe alkaline batteries

A
  • high energy capacity
  • long shelf life
  • once chemical reactants are used = no longer usable
  • power output decreases over time
  • 1.5 V (except PP3, which is 9 V)
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30
Q

Describe rechargable batteries

A
  • can be charged many times
  • will drain whether if you use it or not
  • power output remains constant until it runs flat
  • 1.2 V per cell
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31
Q

Why should batteries be disposed of properly?

A
  • contains toxic chemicals
  • can contaminate the soil and water if left at landfill
  • dispose at recycling centre
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32
Q

What is a modern material?

A
  • discovered or developed since WW2 (1945)
  • materials specifically developed with enhanced properties, through the invention of new or improved processes
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33
Q

What is graphene?

A
  • a single layer of carbon atoms bound togther in a hexagonal lattice
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34
Q

What are graphene’s properties?

A
  • thinnest known material
  • strong, light, conductive
  • used in sports equipment, cooling technology in mobile phones
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35
Q

What is metal foam?

A
  • metal containing gas filled pores
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36
Q

What are the properties of metal foam?

A
  • good stiffness to weight ratio
  • good thermal insulation
  • good sound absorption
  • used for weight saving and impact absorbing structures in vehicles
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37
Q

What are liquid crystal displays? (LCD)

A
  • matrix of pixels that display an image on the screen
  • backlight provides light to individual pixels
  • varies red, blue, green light to make colour combinations
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38
Q

Why are LCDs developed?

A
  • high consumer demand for wearable and large displays, higher definition, longer battery life for portable devices
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39
Q

What are coated metals?

A
  • protects metal, reduces wear and tear (more durable)
  • unprotected ferrous metal is liable to rust
  • eg. galvanised (zinc coated) steel, Teflon (non-stick), anodising (coloured aluminium)
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40
Q

What are nanomaterials?

A
  • materials or substances made at a very small scale
  • less than 100 nanometres in size
  • adds properties to products
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41
Q

What properties can nanomaterials add?

A
  • tensile strength
  • rigidity
  • produce more lightweight products
  • used in electronics + medicine
  • make textiles resistant to bacteria, super hydrophobic, repel dirt, neutralise bad odours
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42
Q

What are smart materials?

A
  • responsive materials that are designed to react to external stimuli. they can alter the functional or aesthetic properties in response to a changing environment.
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43
Q

What is titanium?

A
  • a metal found in the earth’s crust
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44
Q

What are the properties of titanium?

A
  • high strength
  • lightweight
  • resists corrosion
  • does not react with human tissue
  • used to make artificial joints
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45
Q

What is polymorph?

A
  • polymer that can be shaped and reshaped many times
  • when warmed to 62C beomes flexible and easy to mold
  • as it cools it becomes stiff and strong
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46
Q

What is polymorph used for?

A
  • making ergonomic handles
  • prototype mechanical parts
  • mouldings
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47
Q

What is a shape memory alloy? (SMA)

A
  • group of materials that revert back to their original shape after being deformed by heat or another external stimulus
48
Q

What is an example of SMAs?

A
  • Nitinol used in dentistry for braces
  • Nitinol mesh used for expandable stents in vascular surgery
49
Q

What is a quantum tunnelling composite? (QTC)

A
  • flexible polymer with tiny metal particles embedded into it
  • when squeezed current of electrons flows between neighbouring particles
  • electrons jumping across a gap from one conducting material to another is known as quantum tunnelling
  • used in microswitches, touch sensitive pads
50
Q

What is a composite material?

A
  • composed of at least two materials
  • when combined the properties are superior to those of the individual components
  • eg. fire/ corrosion resistance, better strength to weight ratio, better tensile strength
51
Q

What are some disadavantages of composite materials?

A
  • hard to separate and recycle
  • can be expensive
  • resins/ adhesives can cause risks
52
Q

What are thermochromic materials?

A
  • change colour at certain ranges of temperature (cold or hot activation)
  • can be incorportaed into inks and printed onto plastic
  • used in baby safety products, mugs
53
Q

What are photochromic materials?

A
  • change colour when exposed to different UV levels
  • pigments degrade from over exposure to UV light
  • used in glasses
54
Q

What is glass reinforced plastic (GRP)?

A
  • polyester material reinforced with the addition of glass fibre
  • combines thermosetting polyester resin and glass fibre matting
  • strong, lightweight
  • used in circuit boards, pond liner, kayaks
  • cheap but heavier than CFRP
55
Q

What is carbon fibre reinforced plastic? (CFRP)

A
  • thermoplastic reinforced with carbon fibres
  • produced by combining thermoplastic polymer resin with carbon fibre matting using a “lay up” process
  • high strength to weight ratio
  • rigid
  • used in sports equipment, aerospace engineering
56
Q

What are technical textiles?

A
  • made from a combination of natural and synthetic fibres and filaments
  • can be coated, laminated or impregnated to improve the properties and performance of the item
  • used in geotextiles, argotextiles
57
Q

What is Gore-Tex?

A
  • breathable and waterproof
  • allows vapour to escape but pores are too small for water
  • used for outdoor clothing
58
Q

What is Kevlar and what is it made of?

A
  • plastic fibre with high tensile strength
  • made of modified polyamide fibres (from class of fibres called aramids)
  • polyamide molecules connect to form long chains
  • aligned parallel to each other inside the fibres acting as reinforcement
59
Q

What are the properties of Kevlar and what is it used for?

A
  • plastic fibre with high tensile strength
  • heat resistant, extremely hard- wearing
  • flexible and lightweight synthetic fibre
  • cut, puncture, ballistic resistant/ bullet proof
  • make body armour, bullet proof vests, reinforce tyres, add strength and durability to sports equipment
60
Q

How is Kevlar so bullet proof

A
  • projectile hits Kelvar -> fibres “catch” it
  • abosorbs and dissipates its energy
61
Q

What are technical textiles used to make?

A
  • protective clothing in sports, medical, hazardous and industrial enviornments
  • provides chemical protection
  • flame resistance
  • cut resistance
62
Q

What are microfibres?

A
  • synthetic fibres less than one denier thick
  • can be micro-encapuslated
63
Q

What is micro-encapsulation?

A
  • packaging particles or droplets
  • can improve properties of microfibre as they can hold anti-microbial agents, insecticides, medicine etc
  • can release these with control
64
Q

What are fire resistant fabrics?

A
  • designed to withstand heat and resist burning
  • provides protection against heat without melting or dripping
  • eg when Nomex is exposed to heat the fibres thicken and absorb heat energy
65
Q

What are conductive fabrics?

A
  • made from, coated or blended with conductive materials
  • used for thermal heating or allowing electrical signals to pass through with little resistance
  • can have batteries, small lights, electronics embedded into them
  • used in sportsear to monitor vital statistics
66
Q

What does an input device do in a electrical circuit?

A
  • sense that something has changed eg. motion, heat, light, moisture etc
67
Q

What does an process device do in a electrical circuit?

A
  • manipulate/ notice the voltage/ signal from the input to control the output component, usually by switching it on or off
68
Q

Input, process or output?

What does an LDR do?

A
  • detects changes in light levels
  • resistance increases in dark and decreases in light
  • used in street lamps and security lights
69
Q

Input, process or output?

What does a pressure sensor do?

A
  • detects changes in pressure in gases or liquids
  • eg. detect leak in fuel system
  • used to detect weight
  • eg. detect a burgular has stepped on a mat
70
Q

Input, process or output?

What does a switch do?

A
  • switches circuit on or off
  • used in lighting, control panels and power switches
71
Q

Input, process or output?

What does a thermistor do?

A
  • detects change in temperature
  • as temperature increases resistance decreases
  • used in household appliances and vehicles
72
Q

Input, process or output?

What does a resistor do?

A
  • limit the flow of the current
  • protects some components from being overloaded
73
Q

Input, process or output?

What does a microcontroller do?

A
  • programmable component, can be programmed in a variety of programming languages or software that uses flowcharts for programming
  • tiny computer on a single chip
  • can perform the task of multiple ICs
  • used in electrical products such as washing machines
74
Q

What are the advantages of using a microcontroller rather than multiple ICs?

A
  • microcontroller is cheaper than multiple ICs
  • circuit can be made smaller
  • can be updated with software updates/ reprogrammed
75
Q

What can microcontrollers be programmed to do?

A
  • decision making with timing and counting functions
76
Q

What are the symbols used for a flowchart

A
  • start and stop: round rectangle
  • process: rectangle
  • decision (yes or no outcome): rhombus
  • arrow: indicates the flow of instructions
77
Q

What is an open loop system?

A
  • the output does not directly affect the input
  • eg. toaster
78
Q

What is a closed loop system?

A
  • output does directly affect the input
  • eg. house thermostat
79
Q

What is polarity?

A
  • have positive and negative connections
  • must be connected the right way around a circuit otherwise they will not work
80
Q

What is a buzzer?

A
  • gives a sound output
  • electromagnetic wires turn circuit on and off to create buzz
81
Q

What is a lamp?

A
  • uses electricity to produce light of varying levels
82
Q

What is a light emitting diode? (LED)

A
  • low power light used in power indicators and lamps
  • long lasting
83
Q

What is a speaker?

A
  • translate electrical signal into audible sound
84
Q

What is linear motion

A
  • movement in one direction along a straight line
85
Q

What is reciprocating motion?

A
  • repetitive up and down or back and forth linear motion
86
Q

What is rotary motion?

A
  • movement on or around an axis
  • eg. wheel
87
Q

what is oscillating motion?

A
  • movement backwards and forwards along a curved path
  • e.g swing
88
Q

What does a typical lever consist of

A
  • fulcrum: a pivot point around which a lever turns
  • effort: an input force
  • load: an output force
89
Q

how to calculate mechanical advantage

A

MA = load/ effort

90
Q

How to calcualte how much does it need to balance forces

A

force A x distance A = force B x distance B

91
Q

What is a first order lever

A
  • fulcrum is in the middle of effort and load
  • eg. pliers
92
Q

What is a second order lever?

A
  • load is in the middle of the effort and fulcrum
  • eg. wheelbarrow
93
Q

What is a third order lever?

A
  • effort is in the middle of fulcrum and load
  • eg. tweezers
94
Q

What is a reverse motion linkage?

A
  • input & output move in opposite directions
  • eg. clothes dryer
  • Z shape
95
Q

what is a push pull linkage?

A
  • maintains direction of input to output (travels in same direction)
  • eg. windscreen wipers on cars
96
Q

What is a bell crank linkage?

A
  • changes the direction of input motion 90 degrees
  • changes horizontal motion into vertical motion (vice versa)
97
Q

What is a cam used for?

A
  • used to change rotary motion into reciprocating motion using a follower
  • crank is used to rotate the shaft which rotates the cam and moves the follower up and down
98
Q

How does a circular cam or eccentric cam move?

A
  • steady rise and fall
99
Q

how does a pear cam move?

A
  • rapid rise and fall followed by long dwell (rest)
100
Q

How does a snail cam move?

A
  • steady rise and sudden drop
  • only turns in one direction otherwise it would jam
101
Q

Flat follower advantages and disadvantages

A
  • greater load carrying capabilities
  • increased friction
  • less accurate
102
Q

Knife edge follower advantages and disadvantages

A
  • greater accuracy
  • wears quickly
  • large side thrust
103
Q

Roller follower advantages and disadvantages

A
  • reduced friction
  • runs at high speed
  • more complex
  • higher cost
104
Q

What are gears?

A
  • toothed wheels that mesh to transfer motion from one part of a machine to another
105
Q

What is a gear train

A
  • two are more gears meshed together
106
Q

What is torque?

A
  • force that causes rotation
107
Q

What can gears change

A
  • position of the movement
  • direction of rotation
  • speed of rotation
108
Q

What does a drive gear do?

A
  • turns the driven gear
  • gears turn in opposite directions
109
Q

What does an idler gear do?

A
  • change the direction of rotation
  • drive and driven gear = same direction
  • size of idler gear does not affect rotation speed
110
Q

How to calculate gear ratio?

A

gear ratio = number of teeth on driven gear/ number of teeth on drive gear (no units)

111
Q

How to calculate velocity ratio

A
  • rotations of the drive gear/ rotations of driven gear
  • velocity ratio = gear ratio
112
Q

What do pulleys do?

A
  • transmit rotary motion and force from input or drive shaft to the output or driven shaft
  • belts are made with reinforced rubber or high strength materials like Kevlar
113
Q

Compare pulleys to gears

A
  • gears mesh directly while pulleys need a belt to connect
  • meshed gears go in opposite directions whereas pulleys in a system move in the same direction
  • meshed gears have to be positioned very precisely (too close= high friction, too far = wear and fail quickly)
  • gears connected with chain need to be placed quite precisely, chains are made of metal of fixed length
  • pulley belts have some flexibility so distance is not cruicial
  • gears are used for high torque applications (allow for higher torque)
  • if gear becomes stuck driver gear would break
  • if pulley becomes stuck the** belt would slip off the pulley**
114
Q

What is a drive belt?

A
  • loop of flexible rubber
115
Q

Label a diagram of a cam

A
116
Q

How is MDF and chipboard made?

A
  • wood processesd into chips or particles
  • particles are mixed with adhesive (foremaldehyde resin)
  • mixture is compressed into shape with rollers and heated to cure the adhesive
  • boards are trimmed to standard sizes

DT theory GCSE (8 decks)

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