22/04/2017 P2 Living for the Future (OCR) AGAC

22/04/2017 Wind Power

Solar Energy 22/04/2017 Solar cells – convert sunlight directly into electricity. Sunlight knocks electrons loose from the crystal structure and the loose electrons form an electric current. The amount of power depends on the area of the panel and the light intensity. Solar panels provide heating for homes – these pipes carry water that absorbs heat energy and transfers it to the house.

Generating Electricity 22/04/2017 Generating Electricity The direction of the generated current is reversed if… The magnet is moved in the opposite direction The other pole is inserted first The size of the generated current can be increased by: Increasing the speed of movement Increasing the magnet strength Increasing the number of turns on the coil

AC Generator N S N S Induced current can be increased in 4 ways: 22/04/2017 N S N S Current Induced current can be increased in 4 ways: Increasing the speed of movement Increasing the magnetic field strength Increasing the number of turns on the coil Increasing the area of the coil Time

Using non-renewable fuels in power stations 22/04/2017 1) A fossil fuel is burned in the boiler 2) Water turns to steam and the steam drives a turbine 3) The turbine turns a generator 4) The output of the generator is connected to a transformer 5) The steam is cooled down in a cooling tower and reused

Fuels 22/04/2017 A “fuel” is something that can be burned to release heat and light energy. The main examples are: Coal, oil and gas are called “fossil fuels”. In other words, they were made from fossils.

Nuclear power stations 22/04/2017 These work in a similar way to normal power stations: The main difference is that the nuclear fuel is NOT burnt – it is used to boil water in a “heat exchanger”

Words – step down, high, power, low, high The National Grid 22/04/2017 Electricity reaches our homes from power stations through the National Grid: Power station Step up transformer Step down transformer Homes If electricity companies transmitted electricity at 230 volts through overhead power lines there would be too much ______ loss by the time electricity reaches our homes. This is because the current is ___. To overcome this they use devices called transformers to “step up” the voltage onto the power lines. They then “____ ____” the voltage at the end of the power lines before it reaches our homes. This way the voltage is _____ and the current and power loss are both ____. power high step down high low Words – step down, high, power, low, high

Efficiency of Power Stations 22/04/2017 The blue arrows show the energy wasted The red arrows show the useful energy Heat Heat Heat 15J Boiler Turbine Generator 100J 50J 5J 85J 35J 30J Heat Kinetic Electrical This diagram shows that starting with 100 J only 30 J finishes up being useful as electrical energy

Efficiency 22/04/2017 Efficiency is a measure of how much USEFUL energy you get out of an object from the energy you put INTO it. For example, consider a TV: Light (80J) Electrical Energy (200J) Sound (40J) Heat (?) Efficiency = Useful energy out Energy in x100% 120 x100 = 200 60%

Some examples of efficiency… 22/04/2017 500J of electrical energy are put into a motor. The motor converts this into 100J of movement energy. How efficient is it? A laptop can convert 400J of electrical energy into 200J of light and sound. What is its efficiency? Where does the rest of the energy go? A power station is 50% efficient. If it delivers 20,000J of electrical energy how much chemical energy was put into it? 100/500 x100 =20% 200/400 x100 =50% 40,000J

Words – non-renewable, coal, fossil fuels, wood, renewed Some definitions… 22/04/2017 A renewable energy source is clearly one that can be _______ (“renew = make again”), e.g. _____, solar power etc. A ___________ energy source is one that when it has been used it is gone forever. The main examples are ____, oil and gas (which are called ______ ____, as they are made from fossils), and nuclear fuel, which is non-renewable but NOT a fossil fuel. renewed wood non-renewable coal fossil fuels Words – non-renewable, coal, fossil fuels, wood, renewed

Pollution 22/04/2017 When a fuel is burned the two main waste products are _____ dioxide and ________ dioxide. Carbon dioxide is a _________ ___ and helps cause ______ ______ This is produced when any fossil fuels are burned. Sulphur dioxide, when dissolved in _______. causes ___ ___. This is mainly a problem for ____ power stations. Nuclear power stations do not produce these pollutants because they don’t ____ fossil fuels. carbon sulphur global greenhouse gas warming rainwater acid rain coal burn Words – sulphur, coal, global warming, carbon, acid rain, greenhouse gas, rainwater, burn

Non-renewable energy sources 22/04/2017 Advantages Disadvantages Cheap fuel costs Costs a lot of money to decommission a nuclear plant Good for “basic demand” Coal, oil, gas and nuclear Reliable Fuel will run out Short start-up time for gas and oil Pollution – CO2 leads to global warming and SO2 leads to acid rain Nuclear produces little pollution

Renewable energy sources summary 22/04/2017 Advantages Disadvantages Zero fuel costs Unreliable (except for hydroelectric) Don’t produce pollution Wind, tidal, hydroelectric and solar Expensive to build Hydroelectric is good for a “sudden” demand Ugly and the energy produced by them is very “dilute” Solar is good for remote locations (e.g. satellites)

The Cost of Electricity 22/04/2017 Electricity is measured in units called “kilowatt hours” (kWh). For example… A 3kW fire left on for 1 hour uses 3kWh of energy A 1kW toaster left on for 2 hours uses 2kWh A 0.5kW hoover left on for 4 hours uses __kWh 2 A 200W TV left on for 5 hours uses __kWh 1 A 2kW kettle left on for 30 minutes uses __kWh 1

The Cost of Electricity 22/04/2017 To work out how much a device costs we do the following: Cost of electricity = Power (kW) x time (h) x cost per kWh (p) For example, if electricity costs 8p per unit calculate the cost of the following… A 2kW fire left on for 3 hours A 0.2kW TV left on for 5 hours A 0.1kW light bulb left on for 10 hours A 0.5kW hoover left on for 1 hour 48p 8p 8p 4p During the night electricity companies reduce the cost of electricity to around 3p per unit. How much do these appliances cost to run overnight?

Power 22/04/2017 Power is “the rate of doing work”. The amount of power being used in an electrical circuit is given by: P I V Power = voltage x current in W in V in A A 100W bulb runs on a voltage of 25V. What current does it draw? A smaller bulb is powered by a 3V battery with a current of 2A. What is the power rating of this bulb? A 2000W kettle is plugged into a 250V supply. What current does it draw? 4A 6W 8A

The structure of the atom 22/04/2017 ELECTRON – negative, mass nearly nothing PROTON – positive, same mass as neutron (“1”) NEUTRON – neutral, same mass as proton (“1”)

Introduction to Radioactivity 22/04/2017 Some substances are classed as “radioactive” – this means that they are unstable and continuously give out radiation: Radiation The nucleus is more stable after emitting some radiation – this is called “radioactice decay”.

Background Radiation 13% are man-made Radon gas Food Cosmic rays 22/04/2017 13% are man-made Radon gas Food Cosmic rays Gamma rays Medical Nuclear power

Types of radiation 22/04/2017 1) Alpha () – an atom decays into a new atom and emits an alpha particle (2 protons and 2 ______ – the nucleus of a ______ atom) neutrons Unstable nucleus New nucleus Alpha particle helium 2) Beta () – an atom decays into a new atom by changing a neutron into a _______ and electron. The fast moving, high energy electron is called a _____ particle. proton beta Beta particle New nucleus Unstable nucleus 3) Gamma – after  or  decay surplus ______ is sometimes emitted. This is called gamma radiation and has a very high ______ with short wavelength. The atom is not changed. energy frequency Words – frequency, proton, energy, neutrons, helium, beta Unstable nucleus New nucleus Gamma radiation

Blocking Radiation    Sheet of paper Few mm of aluminium 22/04/2017 Each type of radiation can be blocked by different materials:    Sheet of paper Few mm of aluminium Few cm of lead

Handling Radioactive Materials 22/04/2017 Safety measures: Keep your distance Minimise exposure time Protective clothing Careful labelling

Disposing of radioactive waste 22/04/2017 The key to dealing with radioactive waste is to IMMOBILISE it. There are a number of ways of doing this depending on how __________ the waste is: radioactive High level waste is immobilised by mixing with ____ making ingredients, melting and pouring the glass into steel containers. glass Intermediate waste is set in cement in _____ drums. steel The containers are then kept in stores, often _________. underground Words – glass, steel, underground, radioactive

Ionisation 22/04/2017 Radiation is dangerous because it “ionises” atoms – in other words, it turns them into ions by “knocking off” electrons: Alpha radiation is the most ionising (basically, because it’s the biggest). Ionisation causes cells in living tissue to mutate, usually causing cancer.

Uses of Alpha Radiation 22/04/2017 Smoke detectors Alpha emitter +ve electrode -ve electrode Alarm This sets off an alarm Ionised air particles If smoke enters here a current no longer flows

Uses of Beta Radiation Beta detector Rollers Paper Beta emitter 22/04/2017 Beta detector Rollers Paper Beta emitter This is used to make sure the paper/steel is the correct thickness. The pressure on the rollers is adjusted depending on how much of the beta is received by the detector

Uses of Gamma Radiation 22/04/2017 Sterilising medical instruments Gamma rays can be used to kill and sterilise germs without the need for heating.

Other uses of radioactivity 22/04/2017 1) Medical uses – gamma rays can be used to destroy cancerous cells 2) Tracers – a tracer is a small amount of radioactive material used to detect things, e.g. a leak in a pipe: Gamma source The radiation from the radioactive source is picked up above the ground, enabling the leak in the pipe to be detected. Tracers can also be used to develop better plant fertilisers and in medicine to detect tumours:

Comparing magnets and solenoids 22/04/2017 N S Magnet: Solenoid:

The Earth’s Magnetic Field 22/04/2017 This magnetic field gives us protection from ionising cosmic rays see the next two slides

Solar Flares 22/04/2017 Solar flares are clouds of charged particles ejected at high speed from the sun. They can produce strong magnetic fields that interfere with satellites.

22/04/2017 Aurora Borealis

My Very Easy Method Just Speeds Up Naming Planets Our Solar System 22/04/2017 Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto My Very Easy Method Just Speeds Up Naming Planets

Solar systems, galaxies and the Universe 22/04/2017 (Basically, everything in the universe orbits around something else) OUR SUN is one of millions of stars that orbit the centre of… THE MILKY WAY, which is one of a billion galaxies that orbit AND move away from the centre of… THE UNIVERSE

Elliptical Orbits 22/04/2017 Ellipse

The Earth is kept in orbit by 2 things… 22/04/2017 This is called a “centripetal force” Gravity …and by the fact that it is moving at a high velocity

Comets 22/04/2017 Comets are balls of dust and frozen gas. They have very elliptical orbits: As the comet approaches the sun gases evaporate from it, forming a “tail”. This tail always faces AWAY from the sun. The comet also goes faster near the sun.

Asteroids If an asteroid hit the Earth what effect would it have? 22/04/2017 crater; ejection of hot rocks; widespread fires; sunlight blocked by dust; climate change; species extinction. If an asteroid hit the Earth what effect would it have? Many asteroids have already hit the Earth over many years – how do we know? craters/unusual elements

Space Travel Advantages Disadvantages Manned space travel 22/04/2017 Advantages Disadvantages Explain that manned spacecraft need to take food, water and oxygen. Manned space travel enough fuel;  long time required;  effect of low gravity on health;  shielding from cosmic rays;  maintaining a stable atmosphere;  providing enough food and water;  keeping warm. unmanned spacecraft (probes) do not need food, water or oxygen. Unmanned space travel unmanned spacecraft can withstand conditions that are lethal to humans. State that unmanned spacecraft can send back information on: temperature, magnetic field and radiation; gravity, atmosphere and surroundings

Near Earth Objects 22/04/2017 A Near Earth Object (NEO) is an asteroid or comet on a possible collision course with the Earth.

Evidence about the origins of the universe… 22/04/2017 Evidence about the origins of the universe…

Evidence #1 - Microwaves 22/04/2017 When the “Big Bang” happened microwaves were produced and these are still reaching us now. They can sometimes be seen as TV interference.

Evidence #2 - Redshift 22/04/2017 Source of light “Spectra”

If you pass the light through a gas something different is seen… 22/04/2017 If you pass the light through a gas something different is seen… helium Some wavelengths of light are absorbed by the gas – an “absorption spectrum”.

Before helium helium After 22/04/2017 If the light source is moving away the absorption spectra look a little different… helium Before helium After

22/04/2017 The absorption lines have all been “shifted” towards the longer wavelength end (red end)… Before This is called red shift. The faster the light source moves the further its light will be “shifted” After

This is the BIG BANG theory 22/04/2017 Light from different stars and from the edge of the universe also shows this “red-shift”. This suggests that everything in the universe is moving away from a single point. This is the BIG BANG theory

Words to use – faster, away, big bang, billion, wavelength, further Red shift summary 22/04/2017 Light from other galaxies has a longer _________ than expected. This shows that these galaxies are moving ____ from us very quickly. This effect is seen to a greater extent in galaxies that are _______ away from us. This indicates that the further away the galaxy is, the ______ it is moving. This evidence seems to suggest that everything in the universe is moving away from a single point, and that this process started around 15 _____ years ago. This is the ____ ____ Theory. wavelength away further faster billion big bang Words to use – faster, away, big bang, billion, wavelength, further

The Life and Death of a Star 22/04/2017 The Life and Death of a Star

Nebulae A nebulae is a collection of dust, gas and rock. 22/04/2017 A nebulae is a collection of dust, gas and rock. Some examples of nebulae…

22/04/2017 Dark nebula

22/04/2017 Emission nebula

22/04/2017 Planetary nebula

22/04/2017 Reflection nebula

Protostar Gravity will slowly pull these particles together… 22/04/2017 Gravity will slowly pull these particles together… As they move inwards their gravitational potential energy is converted into heat and a PROTOSTAR is formed

Words – heavier, balanced, hydrogen, nuclear, temperatures Main Sequence 22/04/2017 Our sun is an example of a main sequence star – it’s in the middle of a 10 billion year life span In a main sequence star the forces of attraction pulling the particles inwards are _________ by forces acting outwards due to the huge __________ inside the star. Stars are basically ________ reactors that use _______ as a fuel. During its main sequence a star will release energy by converting hydrogen and helium (light elements) into _________ elements. Words – heavier, balanced, hydrogen, nuclear, temperatures balanced temperatures nuclear hydrogen heavier

Red Giants 22/04/2017 Eventually the fuels will run out. When this happens the star will become colder and redder and start to swell… If the star is relatively small (like our sun – a “medium weight star”) the star will become a RED GIANT If the star is big (at least 4 times the size of our sun – a “heavy weight star”) it will become a RED SUPERGIANT

The Death What happens next depends on the size of the star… 22/04/2017 What happens next depends on the size of the star… 1) For medium weight stars the red giant will collapse under its own gravity and form a very dense white dwarf: Red giant Planetary Nebula White dwarf

This explosion is called a SUPERNOVA 2) Heavy weight stars will shrink and then EXPLODE, releasing massive amounts of energy, dust and gas. 22/04/2017 Before After This explosion is called a SUPERNOVA

22/04/2017 The dust and gas on the outside of the supernova are thrown away by the explosion and the remaining core turns into a NEUTRON STAR. If the star was big enough (i.e. ten times heavier than our sun) it could become a BLACK HOLE.

Detecting black holes 22/04/2017 Black holes can’t be detected directly, but their effects on other bodies can be observed. This is a binary system. The black hole sucks in material from its companion star. The material becomes very hot and emits X-rays as it falls into the black hole.