A useful resource for Junior Certificate Science revision.

1. 27/05/13
Science Revision forScience Revision for
Junior CertificateJunior Certificate
Theresa Lowry-Lehnen
RGN, BSc (Hon’s) Specialist Clinical Practitioner (Nursing), Dip Counselling, Dip
Adv Psychotherapy, BSc (Hon’s) Clinical Science, PGCE (QTS) , H. Dip. Ed,
MEd, Emotional Intelligence (Level 9) MHS Accredited

2. 27/05/13
DiffusionDiffusion
Diffusion is when something travels from an area of high
concentration to an area of low concentration. For example,
consider the scent from a hamburger…
The “scent particles” from
this hamburger are in high
concentration here:
Eventually they will
“diffuse” out into this area
of low concentration:

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DiffusionDiffusion
Cells use diffusion to swap
the oxygen they need for
the carbon dioxide they
no longer want:
Other examples of where diffusion happens in humans:
Alveoli in the lungs Villi in the intestines
Oxygen
diffuses in
Out goes
waste CO2

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The digestive systemThe digestive system
The whole point of digestion is to break down our food so
that we can get the bits we need from it…
The main foods
affected are
CARBOHYDRATES –
these are broken down
into GLUCOSE

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EnzymesEnzymes
Enzymes are chemicals produced by the body to help
_______. When they react with food they break it down
into ______ pieces which can then pass into the ______:
Carbohydrase (produced in the mouth,
pancreas and small intestine) breaks
_______ (a carbohydrate) down into
glucose:
Protease (produced in the stomach,
pancreas and small intestine) breaks
_______ down into amino acids:
Lipase (produced in the pancreas and
small intestine) breaks fats (_____)
down into fatty acids and glycerol:
Words – blood, lipids, proteins, digestion, starch, smaller
Bloodstream

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A closer look at alveoli:A closer look at alveoli:
Trachea
Bronchi
Bronchioles
Alveoli

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Gas exchangeGas exchange
Alveoli are very good at exchanging gases because…
1) They have a LARGE surface area
2) They have a good blood supply
3) They are moist

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RespirationRespiration
Respiration is the chemical reaction the cells in our bodies
use to release ________. The equation:
Glucose + _____ Carbon dioxide + _____ + ENERGY
Glucose is provided by ______ and oxygen is provided when
we __________. The energy we obtain from this reaction
was originally contained inside the ________ molecules and
is released when the bonds are ________.
The energy produced by respiration is used for building and
repairing _____, movement, transporting materials across
__________ and maintaining a constant ___________.
Words – water, temperature, membrane, broken,
food, energy, oxygen, glucose, breathe, cells

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Anaerobic respirationAnaerobic respiration
Unlike aerobic respiration, anaerobic respiration is when
energy is provided WITHOUT needing _________:
This happens when the body can’t provide oxygen quick enough
for __________ respiration to take place.
Anaerobic respiration produces energy much _______ than
aerobic respiration but only produces 1/20th
as much.
Lactic acid is also produced, and this can build up in muscles
causing ______ and an oxygen ______.
This “debt” then needs to be “repaid” by deep breathing to
________ the lactic acid.
Words – debt, oxygen, fatigue, oxidise, aerobic, quicker
Glucose lactic acid + a bit of energy

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The four parts of bloodThe four parts of blood
1. RED BLOOD CELLS – contain haemoglobin
and carry ______ around the body. They
have no _______ and a large surface area.
2. PLATELETS – small bits of cells that lie
around waiting for a cut to happen so that
they can ____ (for a scab).
3. WHITE BLOOD CELLS – kill invading
_______ by producing _________ or
engulfing (“eating”) the microbe.
These three are all carried around by the
PLASMA (a straw-coloured liquid). Plasma
transports CO2 and ______ as well as taking
away waste products to the ______.
Words – antibodies, clot, kidneys,
oxygen, nucleus, glucose, microbes.

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Section 2Section 2
Maintenance of LifeMaintenance of Life

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PhotosynthesisPhotosynthesis
PHOTOSYNTHESIS is when a plant makes its own food.
Photosynthesis USES:
Carbon dioxide
Water
Energy (from the sun)
Photosynthesis PRODUCES:
Oxygen
Glucose

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Four things are needed for photosynthesis:
Travels up
from the roots
WATER
CARBON DIOXIDE
Enters the leaf through small
holes on the underneath
SUNLIGHT
Gives the plant energy
CHLOROPHYLL
The green
stuff
where the
chemical
reactions
happen

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The word and chemical equations for photosynthesis:
Carbon dioxide + water glucose + oxygen
6CO2 + 6H20 C6H12O6 + 6O2
Sunlight
Chlorophyll
Sunlight
Chlorophyll
Glucose (sugar) can be used to make long chains of starch…
Glucose
molecules
Starch
molecule

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Three factors can affect photosynthesis:Three factors can affect photosynthesis:
1. Temperature – the best temperature is
about 300
C – anything above 400
C will slow
photosynthesis right down
2. CO2 – if there is more carbon dioxide
photosynthesis will happen quicker
3. Light – if there is more light
photosynthesis happens faster

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Drawing graphs of these factorsDrawing graphs of these factors
1. Temperature
Photosynthesis is controlled by
enzymes – these are destroyed
at temperatures above 400
C
2. Carbon dioxide
3. Light
Photosynthesis increases at
first but is then limited by a
lack of increase in temp or CO2
Photosynthesis increases at
first but is then limited by a
lack of increase in temp or light

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HomeostasisHomeostasis
Homeostasis means “controlling internal conditions”:
Waste products that need to be removed + how
CO2
Urea
Internal conditions that need controlling + how
Temperature
Ion content
Water content
Produced by respiration, removed via lungs
Produced by liver breaking down amino acids,
removed by kidneys and transferred to bladder
Increased by shivering, lost by sweating
Increased by eating, lost by sweating + urine
Increased by drinking, lost by sweating + urine
Some of these processes are controlled by HORMONES. Hormones are
chemical messengers produced by glands and transported in the blood.

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KidneysKidneys
Blood in
Blood out
Ureter (tube that takes
urine down to bladder)
Kidneys are made up of two
important tissues – BLOOD
VESSELS and TUBULES.
Kidneys are responsible for controlling ion, urea and
water content.

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KidneysKidneys
Kidneys work in 3 stages:
1. ULTRAFILTRATION - Lots of water and
products of digestion are squeezed out of
the blood and into tubules under pressure.
3. WASTE – excess water, excess ions and
any urea are now removed through the
ureter
2. SELECTIVE REABSORPTION – the blood
takes back the things it wants (e.g. glucose
and ions) even though this means going
against a concentration gradient.
Blood vessel Tubule

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Controlling water contentControlling water content
The amount of water reabsorbed into the blood vessels in
the kidney is controlled by the hormone ADH:

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Controlling body temperatureControlling body temperature
Body temperature is controlled by the thermo-regulatory
centre in the ________. It is kept at 370
C as this is the
best temperature for __________ to work in. If the body
becomes too hot then blood vessels _________ and sweat
glands release ________. If the body is too ______ then
blood vessels constrict and muscles start to __________.
Words – sweat, enzymes, cold, dilate, shiver, brain

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Section 3Section 3
MetalsMetals

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Section 4 - MetalsSection 4 - Metals
Metals Non-metals
Properties? Properties?

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Group 1 – The alkali metalsGroup 1 – The alkali metals
Li
Na
K
Rb
Cs
Fr

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Group 1 – The alkali metalsGroup 1 – The alkali metals
1) These metals all have to be
stored under ____ because they
react with _______
Some facts…
2) Reactivity increases as you go _______ the group. This is
because the electrons are further away from the _______
every time a _____ is added, so they are given up more easily.
3) They all react with water to form an alkali (hence their
name) and __________, e.g:
Words – down, oil, shell, hydrogen, nucleus, water
Potassium + water potassium hydroxide + hydrogen

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The Transition MetalsThe Transition Metals
1) This section includes metals like gold, mercury, iron, copper
Some facts…
2) They are all ______ and solid (except _________)
3) They are ____ reactive than the alkali metals
Words – hard, coloured, mercury, less
4) They can form __________ compounds

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The Reactivity SeriesThe Reactivity Series
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
Platinum

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Displacement ReactionsDisplacement Reactions
A displacement reaction is where a more reactive metal will displace a
less reactive metal from one of its compounds.
e.g.
Predict the following reactions:
1) Lead + copper chloride
2) Silver + copper chloride
3) Magnesium + iron oxide
4) Aluminium + copper sulphate
5) Zinc + lead nitrate
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
Platinum

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Extracting MetalsExtracting Metals
Some definitions:
A METAL ORE is a mineral or mixture of minerals from
which it is “economically viable” to extract some metal.
Most ores contain METAL OXIDES (e.g. rust = iron oxide).
To “extract” a metal from a metal oxide we need to
REDUCE the oxygen. This is called a REDUCTION
reaction.

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How do we do it?How do we do it?
Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
Platinum
Metals ABOVE CARBON, because
of their high reactivity, are
extracted by ELECTROLYSIS
Metals BELOW CARBON are
extracted by heating them with
carbon in a BLAST FURNACE
These LOW REACTIVITY metals
blatantly won’t need to be extracted
because they are SO unreactive you’ll
find them on their own, not in a metal
oxide

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Extracting metalsExtracting metals
1) What is an ore?
2) In what form are metals usually found in the Earth?
3) How do you get a metal out of a metal oxide?
4) What is this type of reaction called?
Type of metal Extraction process Examples
High reactivity (i.e
anything above carbon)
Middle reactivity (i.e.
anything below carbon)
Low reactivity

32. 27/05/13
Acids and alkalisAcids and alkalis
Using a Universal Indicator we can detect what pH a
solution is by observing the colour:
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1 2 3 4 5 6 7 8 9 10 11 12 13
14

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Neutralisation reactionsNeutralisation reactions
Acid + Alkali Salt + Water
1) Sulphuric acid + potassium hydroxide
2) Nitric acid + calcium hydroxide
3) Hydrochloric acid + calcium hydroxide
4) Nitric acid + potassium hydroxide
5) Sulphuric acid + sodium hydroxide
Acids: Hydrochloric acid
Sulphuric acid
Nitric acid
Alkalis: Sodium hydroxide
Calcium hydroxide
Potassium hydroxide
E.g. hydrochloric acid + sodium hydroxide sodium chloride + water

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Section 4Section 4
Earth MaterialsEarth Materials

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Hydrocarbons and crude oilHydrocarbons and crude oil
Longer chains mean…
1. Less ability to flow
2. Less flammable
3. Less volatile
4. Higher boiling point
Increasinglength
Crude oil is a mixture of HYDROCARBONS
(compounds made up of carbon and hydrogen).
Some examples:
Ethane
C C
HH
H
HH
H
Butane
C C
HH H
HH
H C C H
H
HH

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Fractional distillationFractional distillation
Crude oil can be separated by fractional distillation. The oil is evaporated
and the hydrocarbon chains of different lengths condense at different
temperatures:
Fractions with
low boiling
points condense
at the top
Fractions with
high boiling
points condense
at the bottom

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CrackingCracking
Shorter chain hydrocarbons are in greater demand because
they burn easier. They can be made from long chain
hydrocarbons by “cracking”:
Butane
Ethane
Ethane
For example, this bond
can be “cracked” to give
two of these:

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CrackingCracking
This is a THERMAL DECOMPOSITION reaction,
with clay used as a catalyst
1) Carbon dioxide causes the _________ effect
2) Sulphur dioxide causes _____ _____
3) Plastics are not _____________
Cracking is used to produce plastics such as polymers and polyethanes. The
waste products from this reaction include carbon dioxide, sulphur dioxide
and water vapour. There are three main environmental problems here:

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AlkenesAlkenes
Alkenes are different to alkanes; they contain DOUBLE
COVALENT bonds. For example:
Ethane Ethene
Butane Butene
This double bond means that alkenes have the potential to join
with other molecules – this make them REACTIVE. We can
test for alkenes because they turn bromine water colourless.
ALKANES
ALKENES

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Carbon dioxide in the atmosphereCarbon dioxide in the atmosphere
The amount of CO2 in the atmosphere is affected by 3 things:
1) Geological activity moves carbonate rocks deep into
the Earth and they release ______ _______ into the
atmosphere during volcanic activity.
2) When fossil fuels are burned the carbon
contained in them reacts with _____ to form CO2.
3) Increased CO2 in the atmosphere causes a reaction
between it and _______. These reactions produce two things:
INSOLUBLE CARBONATES (which are deposited as ______)
and SOLUBLE HYDROGENCARBONATES (which ________ in
the seawater). These reactions do not remove ALL of the new
CO2 so the greenhouse effect is still getting _______!
Words – oxygen, seawater, carbon dioxide, worse, dissolve, sediment

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The CrustThe Crust
Sedimentary rocks
settle in layers.
The oldest rock is
at the bottom.
Layers of sedimentary rock can be examined to discover how
they were formed. They are often found folded or fractured:

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Section 5Section 5
EnergyEnergy

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RadiationRadiation
When you wear a black t-shirt on a hot, sunny day you would
feel ______ than if you wore ____. This is because black
_______ infrared radiation (i.e. heat) from the sun better
than white does.
I’m very hot!I’m cool!

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Some examples of radiationSome examples of radiation

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Some examples of radiationSome examples of radiation

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Radiation is when heat moves around in electromagnetic _________ like
light does. Any hot object will emit heat radiation – the hotter it is, the
more radiation it emits. This type of radiation is called __________, and
too much of it will cause _________. Dark, matt colours will absorb AND
emit the _____ infra-red radiation, and light, shiny colours will ________
it.
The main difference with radiation is that conduction and convection could
ONLY happen in solids, liquids or gases, whereas radiation will happen
through an _____ _____. This is just as well, as otherwise we wouldn’t be
able to get any heat from the ___.
RadiationRadiation
Words – sun, reflect, infra-red, waves, most, empty space, sunburn
Anything HOT emits HEAT RADIATION – the hotter it
is, the more infra red radiation it emits

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House insulationHouse insulation
Draught excluders
Double
glazing
Loft insulation
Cavity wall
insulation

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House insulationHouse insulation
Type of
insulation
Cost Annual amount
saved
Loft insulation £400 £80
Double Glazing £2,000 £50
Cavity wall ins. £600 £60
Draught excluder £40 £20

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The 9 types of energy and Energy transfersThe 9 types of energy and Energy transfers
Kinetic (movement)
Sound
Light
Heat
Nuclear
Electrical
Chemical
Gravitational
potential
Elastic potential
What are the energy changes
of the following devices?
1) A TV
2) A car engine
3) A battery
4) An electric motor
5) A bow and arrow
6) A skier skiing down a hill
7) Solar panels

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EfficiencyEfficiency
Efficiency is a measure of how much USEFUL energy you get out of
an object from the energy you put INTO it.
Efficiency = Useful energy given out by the device
Energy put into it
e.g. if 2000 joules of electrical energy are put into a kettle and 500
joules of heat energy are gained from it, its efficiency is 500/2000
x 100% = 25%
x100%
1) How efficient is a 3kW electric fire if it gives out 750W of heat?
2) How efficient is a TV that gives out 30J of wasted energy for
every 50J of electrical energy? Where does this waste energy
go?

51. 27/05/13
Some examples of efficiency…Some examples of efficiency…
1) 5000J of electrical energy are put into a motor. The
motor converts this into 100J of movement energy.
How efficient is it?
2) A laptop can convert 400J of electrical energy into
240J of light and sound. What is its efficiency?
Where does the rest of the energy go?
3) A steam engine is 50% efficient. If it delivers
20,000J of movement energy how much chemical
energy was put into it?

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Energy Transfer diagramsEnergy Transfer diagrams
Consider a light bulb. Let’s say that the bulb runs on 100
watts (100 joules per second) and transfers 20 joules per
second into light and the rest into heat. Draw this as a
diagram:
100 J/s
electrical
energy
“Input” energy “Output” energy
80 J/s heat
energy (given to
the surroundings)
20 J/s
light energy

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Example questionsExample questions
Consider a kettle:
1) Work out each energy value.
2) What is the kettle’s
efficiency?
Sound
energy
Wasted
heat
Heat to
water
2000 J/s
electrical
energy
Consider a computer:
150 J/s
electrical
energy
10 J/s
wasted
sound
20 J/s
wasted
heat
Useful
light and
sound
1) How much energy is converted
into useful energy?
2) What is the computer’s
efficiency?

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Non-renewable energy sourcesNon-renewable energy sources
Coal, oil, gas and
nuclear
Advantages Disadvantages
Cheap fuel costs
Short start-up time
Good for “basic
demand”
Fuel will run
out
Costs a lot of
money to
decommission a
nuclear plant
Pollution – CO2 leads to
global warming and SO2
leads to acid rain
Reliable

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Renewable energy sourcesRenewable energy sources
Wind, tidal,
hydroelectric and solar
Advantages Disadvantages
Zero fuel costs
Hydroelectric
is good for a
“sudden”
demand
Don’t produce
pollution
Tidal barrages destroy the
habitats of wading birds
and hydroelectric schemes
involve flooding farmland
Unreliable
(except for
hydroelectric)
Expensive
to build
Solar is good for
remote locations
(e.g. satellites)

56. 27/05/13
Renewable energy sourcesRenewable energy sources
Wind – free energy but very “dilute”,
depends on weather, visual pollution
Tidal – as with wave power
Wave – free energy but can harm
wildlife and cause visual pollution. As
with wind, energy is “dilute”
Hydroelectric – Can provide instant
energy but can destroy ecosystems

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Section 6Section 6
ElectricityElectricity

58. 27/05/13
Basic ideas…Basic ideas…
Electric current is when electrons start to flow around a
circuit. We use an _________ to measure it and it is
measured in ____.
Potential difference (also called _______) is
how big the push on the electrons is. We use a
________ to measure it and it is measured in
______, a unit named after Volta.
Resistance is anything that resists an electric current. It is
measured in _____.”
Words: volts, amps, ohms, voltage, ammeter, voltmeter

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Georg Simon Ohm
1789-1854
ResistanceResistance
Resistance is anything that will
RESIST a current. It is measured
in Ohms, a unit named after me.
The resistance of a component can be
calculated using Ohm’s Law:
Resistance = Voltage (in V)
(in Ω) Current (in A)
V
RI

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An example question:An example question:
V
A
1) What is the resistance across
this bulb?
2) Assuming all the bulbs are the
same what is the total resistance
in this circuit?
Voltmeter
reads 10V
Ammeter
reads 2A

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More examples…More examples…
12V
3A
3A
6V
4V
2A
1A
2V
What is the
resistance of
these bulbs?

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ResistanceResistance
Resistance is anything that opposes an electric current.
Resistance (Ohms, Ω) = Potential Difference (volts, V)
Current (amps, A)
What is the resistance of the following:
1) A bulb with a voltage of 3V and a current of 1A.
2) A resistor with a voltage of 12V and a current of 3A
3) A diode with a voltage of 240V and a current of 40A
4) A thermistor with a current of 0.5A and a voltage of
10V

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Current-voltage graphsCurrent-voltage graphs
I
V
I
V
I
V
1. Resistor 3. Diode2. Bulb
Current
increases in
proportion to
voltage
When current through
the bulb increases its
temperature increases,
thereby increasing its
resistance
Behaves like a
resistor, but only
lets current flow
in one direction

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Three simple components:Three simple components:
1) Diode – only lets current flow in one direction
2) Light dependant resistor – resistance DECREASES when
light intensity INCREASES
3) Thermistor – resistance DECREASES when temperature
INCREASES

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Examples of electromagnetsExamples of electromagnets
1. Speaker 2. Relay switch

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ElectromagneticElectromagnetic
inductioninduction
The direction of the induced
current is reversed if…
1) The magnet is moved in the
opposite direction
2) The other pole is inserted
first

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ElectromagneticElectromagnetic
inductioninduction
The size of the induced current
can be increased by:
1) Increasing the speed of
movement
2) Increasing the magnet
strength
3) Increasing the number of
turns on the coil

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AC GeneratorAC Generator
Induced current can be increased in 4 ways:
1) Increasing the speed of movement
2) Increasing the magnetic field strength
3) Increasing the number of turns on the coil
4) Increasing the area of the coil

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Section 7Section 7
Physics in ActionPhysics in Action

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Electronic systemsElectronic systems
Electronic systems are made up of 3 parts:
1) An INPUT SENSOR – these detect changes in the
environment
Examples:
3) An OUTPUT DEVICE – these are controlled by the
processor
Examples:
2) A PROCESSOR – these decide what action is needed
Examples:

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The RelayThe Relay

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RelaysRelays
Circuits such as those containing logic gates only take very ______
currents. These circuits may be needed to operate a device that takes
a much _____ current, e.g. a _________. To do this the circuit would
need a RELAY switch, a device made of an _______ that can operate a
switch. A relay switch is activated by the small current and the switch
part is placed in the circuit needing a large current:
Symbol
for relay:
Words – motor, larger,
electromagnet, small
M

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Logic gatesLogic gates
Logic gates are the basics
behind any kind of
processor. There are 3
that you need to know for
GCSE:
NOT gate – “the output is
NOT what the input is”
AND – “the output is on if A
AND B are both on”
OR – “the output is on if A
OR B are on”
Input Output
0 1
1 0
Input A Input B Output
0 0 0
0 1 0
1 0 0
1 1 1
Input A Input B Output
0 0 0
0 1 1
1 0 1
1 1 1

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Logic gate symbolsLogic gate symbols
NOT gate:
AND gate:
OR gate:

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Some problems to solveSome problems to solve
• The pump on a central heating system is switched on at room
temperature if the system is switched on (with the slide switch).
When the temperature rises the pump needs to be switched off.
• Design a circuit that will sound a buzzer if the temperature of a
hot radiator falls during the day ONLY. Include a test switch to
check the operation of the buzzer.
• Design a circuit for a gardener that will warn them of cold
conditions at night. The alarm should be able to be switched off.

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Potential DividersPotential Dividers
0V
VIN
VOUT
0V
R1
R2
(R1 + R2)
VIN x
(R2)
VOUT
The Potential Divider equation:

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Some example questionsSome example questions
0V
12V
VOUT
0V
100 Ω
100 Ω
0V
1.5V
VOUT
0V
50 Ω
45 Ω
0V
50V
VOUT
0V
10 Ω
75 Ω
0V
3V
VOUT
0V
75 Ω
25 Ω

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Practical applicationsPractical applications
0V
Vin
VOUT
Here’s a potential
divider that is used to
control light-activated
switches…
When the light intensity on the LDR decreases its
resistance will ________. This causes VOUT to _______
so the processor and output will probably turn _____. The
variable resistor can be adjusted to change the ________
of the whole device.
Words – decrease, sensitivity, increase, off

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The CapacitorThe Capacitor
A capacitor is a device that can store charge (it has a
“capacity”). It is basically made of two plates:
…or…
Charge builds up on these plates and the voltage
between them increases until it reaches the supply
voltage.

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Charging and discharging a capacitorCharging and discharging a capacitor
P.d. across
capacitor
Time
P.d.
Time
P.d.
Time Time
Increase
resistance or
capacitance
Increase
resistance or
capacitance

81. 27/05/13
Electronic systemsElectronic systems
System Advantages Disadvantages
CCTV
Internet
Mobile Phones

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Converging and diverging lensesConverging and diverging lenses
CONVERGING (Convex)
Thickest at the centre
DIVERGING (Concave)
Thinnest at the centre

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Ray diagramsRay diagrams
The rays of light are
refracted INWARDS and
meet at the focus, F.
The image formed is REAL –
in other words, it can be
seen on a screen
The rays of light are
refracted OUTWARDS.
A VIRTUAL image is formed
– in other words, the image
doesn’t actually exist
F
F

84. 27/05/13
Ray diagramsRay diagrams
To draw ray diagrams follow these two rules:
1) Draw a ray from the TOP of the object PARALLEL to
the axis and then going through F:
2) Draw a ray from the TOP
of the object going through
the CENTRE of the lens
(which will be undeviated)
F
This image is
REAL, UPSIDE
DOWN and
SMALLER than
the object

85. 27/05/13