P2

THE SUN

• ULTIMATE SOURCE OF MOST OF OUR ENERGY - MOSTLY IN FORM OF HEAT AND LIGHT - SOME STORED ON EARTH AS FOSSIL FUELS - WIND ENERGY CAN BE TRACED BACK TO SUN (SUN HEATS AIR, HOT AIR RISES, COLD AIR TAKES ITS PLACE)
• SUNS ENERGY CAN BE USED DIRECTLY - PHOTO CELLS AND SOLAR HEATING

CURVED MIRRORS

• CONCENTRATE ENERGY FROM SUN - FOCUS SUNS LIGHT AND HEAT
• SINGLE CURVED MIRROR - CAN BE USED AS A SOLAR OVEN
• LARGE CURVED MIRRORS OR COMBINATION OF LOTS OF SMALLER ONES - USED TO GENERATE STEAM TO PRODUCE ELECTRICITY
• ALL DEVICES THAT COLLECT ENERGY FROM SUN MOST EFFICIENT IF THEY TRACK SUNS MOVEMENT ACROSS SKY - COLLECTORS POINTED DIRECTLY AT SUN - CAN CAPTURE MAXIMUM AMOUNT OF HEAT AND LIGHT 

PHOTOCELLS

• GENERATE DIRECT CURRENT (FLOWS THE SAME WAY AROUND THE CIRCUIT ALL THE TIME)
• MADE OF SILICON, A SEMICONDUCTOR - WHEN SUNLIGHT FALLS ON CELL THE SILICON ATOMS ABSORB SOME OF THE ENERGY, KNOCKING LOSE SOME ELECTRONS - ELECTRONS FLOW AROUND CIRCUIT - ELECTRICITY
• CURRENT AND POWER OUTPUT DEPENDS ON:
  • SURFACE AREA (BIGGER = MORE ELECTRICITY)    
  • INTENSITY OF LIGHT (BRIGHTER = MORE ELECTRICITY)
  • DISTANCE FROM LIGHT SOURCE - CLOSER TO CELL = MORE ELECTRICITY)
• ADVANTAGES  - NO MOVING PARTS - STURDY. LOW MAINTENANCE, LAST A LONG TIME
• DISADVANTAGES - NO SUNLIGHT, NO POWER - DON'T WORK AT NIGHT OR WHEN WEATHER'S BAD
  • DON'T NEED POWER CABLES OR FUEL
  • RENEWABLE ENERGY SOURCE - WON'T RUN OUT

PASSIVE SOLAR HEATING - ENERGY FROM SUN USED TO HEAT SOMETHING DIRECTLY

• CAN REDUCE ENERGY NEEDED TO HEAT A BUILDING 
• GLASS LETS IN HEAT AND LIGHT FROM SUN - ABSORBED BY THINGS, HEATING THEM UP
• LIGHT FROM SUN - SHORT WAVELENGTH - CAN PASS THROUGH GLASS INTO ROOM
• HEATED THINGS IN ROOM EMIT INFARED RADIATION - OF A LONGER WAVELENGTH - CAN'T ESCAPE THROUGH WINDOWS BUT IS REFLECTED BACK
• WORKS TO HEAT THINGS UP AND KEEP HEAT INSIDE BUILDING

SOLAR WATER HEATERS

• USE PASSIVE SOLAR HEATING - GLASS LETS HEAT AND LIGHT FROM SUN IN - ABSORBED BY BLACK PIPES AND HEAS UP WATER
• CAN BE USED FOR WASHING OR PUMPED TO RADIATORS TO KEEP BUILDING WARM

WIND TURBINES - CONVERTS KINETIC ENERGY FROM WIND TURNING BLADES ON TURBINE INTO ELECTRICITY

• WIND TURBINES PUT IN EXPOSED PLACES E.G. THE COAST, OUT AT SEA - SUN HEATS ATMOSPHERE, CAUSING CONVECTION CURRENTS - PRODUCES WIND

ADVANTAGES

• CHEAP TO RUN - TOUGH, RELIABLE, WIND IS FREE
• DOESN'T PRODUCE ANY POLLUTING WASTE
• RENEWABLE ENERGY RECOURCE - WON'T RUN OUT

DISADVANTAGES

• NEED 1500 WIND TURBINES TO REPLACE ONE COAL POWERED POWER STATION - CREATE VISUAL AND NOISE POLLUTION
• NO WIND, NO POWER - IMPOSSIBLE TO INCREASE SUPPLY WHEN THERE'S HIGH DEMAND
• DIFFICULT TO FIND SUITABLE PLACES TO BUILD TURBINES - NEED TO BE SPACED OUT AND IN WINDY PLACES
• EXPENSIVE TO SET UP A WIND FARM

THE NATIONAL GRID

NETWORK OF PYLONS AND CABLES THAT COVERS THE WHOLE COUNTRIES - TAKES ELECTRICITY FROM POWER STATIONS TO WHERE ITS NEEDED IN HOMES AND INDUSTRY - ENABLES POWER TO BE GENERATED ANYWHERE ON GRID AND SUPPLIED ANYWHERE ELSE ON GRID

POWER STATIONS

• 1 - BOILER USES FUEL TO PRODUCE HEAT WHICH GENERATES STEAM
• 2 - MOVING STEAM DRIVES BLADES OF TURBINE
• 3 - ROTATING MOVEMENT OF TURBINE CONVERTED INTO ELECTRICITY BY GENERATOR USING ELECTROMAGNETIC INDUCTION AND THE POWER THEN GOES TO THE NATIONAL GRID
• POWER STATIONS ARE INEFFICIENT - OVER HALF ENERGY PRODUCED WASTED AS HEAT AND NOISE

DIFFERENT POWER SOURCES

• FOSSIL FUELS - READILY AVAILABLE, CONCERNTRATED SOURCE OF ENERGY BUT CAUSE ACID RAIN AND MAKE CARBON DIOXIDE. HAVE TO BUY THEM FROM OTHER COUNTRIES AND WILL RUN OUT
• BIOMAS - STUFF FROM PLANTS OR ANIMALS THAT CAN BE FERMENTED TO PRODUCE METHANE - RENEWABLE AND WE CAN QUICKLY MAKE MORE, CARBON NEUTRAL - NOT THAT CONCENTRATED
• NUCLEAR POWER - USING HEAT RELEASED BY URANIUM - DISPOSAL OF WASTE DANGEROUS - CONCERNTRATED SOURCE OF ENERGY, READILY AVAILABLE - NON RENEWABLE
• PHOTOCELLS - ABSORB ENERGY FROM SUN CONVERTED INTO ELECTRICITY - RENEWABLE AND ENVIRONMENTALLY FRIENDLY - NO SUNLIGHT, NO POWER
• WIND POWER - RENEWABLE, ENVIRONMENTALLY FRIENDLY, NO WIND, NO POWER - VISUAL POLLUTION AND SOUND POLLUTION - WIND FARMS EXPENSIVE TO SET UP

ELECTROMAGNETIC INDUCTION - CREATION OF VOLTAGE (AND MAYBE CURRENT) IN A WIRE WHICH IS EXPERIENCING A CHANGE IN MAGNETIC FIELD

THE DYNAMO EFFECT - USING ELECTROMAGNETIC INDUCTION TO TRANSFORM KINETIC ENERGY INTO ELECTRICAL ENERGY

• TWO DIFFERENT SITUATIONS OF EM INDUCTIONPRODUCES ALTERNATING CURRENT - DIRECTION OF MOVEMENT REVERSED THEN VOLTAGE REVERSED TOO
  • AN ELECTRICAL CONDUCTOR (COIL OF WORE) MOVES THROUGH A MAGNETIC FEILD
  • A MAGNETIC FIELD THROUGH AN ELECTRICAL CONDUCTOR CHANGES (GETS BIGGER, SMALLER OR REVERSES)
• TO GET A BIGGER VOLTAGE OR CURRENT, YOU CAN INCREASE
  • THE STRENGTH OF THE MAGNET
  • THE NUMBER OF TURNS ON THE COIL
  • THE SPEED OF MOVEMENT

 EFFICIENCY = (USEFUL ENERGY OUTPUT / TOTAL ENERGY INPUT) X 100

• POWER STATIONS PRODUCE A LOT OF WASTE ENERGY - E.G. HEAT LOST TO ENVIRONMENT
• TOTAL ENERGY = USEFUL ENERGY (ELECTRICITY) + WASTED ENERGY

GENERATORS - ROTATE IN A COIL OF A MAGNETIC FIELD

• EVERY HALF TURN THE CURRENT IN THE COIL SWAPS DIRECTION - (WHEN ROTATING, ANY ONE PART OF THE COIL IS HEADING TOWARDS THE MAGNETS SOUTH POLE FOR ONLY HALF A TURN AND THEN IT HEADS BACK UP TOWARDS NORTH POLE)
• MEANS THAT GENERATORS PRODUCE ALTERNATING CURRENT            --------->
• TURN COIL FASTER - PRODUCES MORE PEAKS AND A HIGHER VOLTAGE AND CURRENT - CURVE ON GRAPH WOULD BE CLOSER TOGETHER (MORE CYCLES PER SECOND) AND TALLER (REACHING HIGHER VOLTAGE)
• FREQUENCY OF AC CURRENT MEASURED IN HZ 
• IN UK, ELECTRICITY HAS 50HZ (COIL IN GENERATOR AT POWER STATION ROTATING 50 TIMES PER SECOND)

BATTERIES - DC ELECTRICITY

• DIRECT CURRENT
• CURRENT PLOTTED ON GRAPH WOULD BE A STRAIGHT LINE

DYNAMOS ON BIKES - WORK SLIGHTLY DIFFERENTLY - ROTATE MAGNET NEAR A COIL - EXACTLY THE SAME CONCEPT - STILL USING EM INDUCTION

THE EARTHS ATMOSPHERE

• EARTH SURROUNDED BY ATMOSPHERE MADE UP OF VARIOUS GASSES - THE AIR
• GASES IN ATMOSSPHERE FILTER OUT CERTAIN TYPES OF RADIATION FROM SUN BY ABSORBING AND REFLECTING RADIATION OF CERTAIN WAVELENGTHS (INFARED)
• WAVELENGTHS OF SOME RADIATION (MAINLY VISIBLE AND RADIO) PASS THORUGH ATMOSPHERE

THE GREENHOUSE EFFECT

• EARTH ABSORBS SHORT WAVELENGTH EM RADIATION FROM SUN - WARMS EARTHS SURFACE
• EARTH THEN EMITS SOME OF THIS RADIATION AT A LONGER WAVE LENGTH (INFARED) BACK INTO SPACE - COOLS DOWN
• A LOT OF INFARED RADIATION ABSORBED BY ATMOSPHERIC GASES E.G. CO2, METHANE, WATER VAPOUR
• GASES THEN RE-RADIATE HEAT IN ALL DIRECTIONS INCLUDING BACK TOWARDS EARTH
• ATMOSPHERE ACTS AS INSULATING LAYER - STOPS EARTH LOSING HEAT AT NIGHT
• WITHOUT GREENHOUSE GASES (CO2, METHANE, WATER VAPOUR), EARTH WOULD BE A LOT COLDER

INCREASING GREENHOUSE GASES

• CARBON DIOXIDE - AVAILABILITY OF ENERGY - USING MORE ENERGY (E.G. DRIVING CARS) THAT WE GET FROM BURNING FOSSIL FUELS - BURNING FOSSIL FUELS RELEASES CO2
• INCREASED POPULATION - MORE LAND NEEDED FOR HOUSES AND FOOD - SPACE OFTEN MADE BY CHOPPING DOWN TREES AND BURNING THEM - FEWER TREES MEANS LESS CO2 IS ABSORBED AND BURNING RELEASES MORE 
• CO2 COMES FROM NATURAL SOURCES E.G. RESPIRATION OF ANIMALS AND PLANTS, VOLCANIC ERUPTIONS
• METHANE - GROWING POPULATION - CATTLE FARMING INCREASED TO FEED IT - CATTLE DIGESTION PRODUCES METHANE
• LANDFILL SITES - DECAYING WASTE PRODUCES METHANE - AMOUNT OF WASTE GROWING
• MATHANE COMES FROM NATURAL SOURCES E.G. VOLCANOES, WETLANDS, WILD ANIMALS
• WATER VAPOUR - NATURAL SOURCES - OCEANS, SEAS RIVERS, LAKES - WATER VAPOUR COULD INCREASE AS GLOBAL TEMPERATURE INCREASES
• POWER STATIONS - PRODUCE WATER VAPOUR - EFFECTS AMOUNT IN LOCAL AREA

CLIMATE CHANGE AND GLOBAL WARMING

• AS GREENHOUSE GASES INCREASE (GREENHOUSE EFFECT), SO DOES THE TEMPERATURE OF THE EARTH
• CLIMATE VARIES NATURALLY BUT SCIENTISTS SAY THAT NATURAL CHANGES DON'T EXPLAIN THE GRADUAL HEATING UP OF THE EARTH - THIS IS DUE TO HUMAN ACTIVITY CAUSING INCREASE OF GASES
• NEW SCIENTIFIC CONSENSUS - HUMANS CAUSING GLOBAL WARMING

CAUSES 

• CLIMATE VERY COMPLICATED - CONDITIONS IN ATMOSPHERE, OCEANS AND LAND EFFECT ONE ANOTHER E.G. GLOBAL WARMING AFFACTS WEATHER - LONGER DROUGHTS - WATER WARMS UP - CAUSES HURRICANES -
• EFFECTS ABILITY TO GROW FOOD - TOO DRY OR TOO WET - WORSEN AS GLOBAL WARMING INCREASES
• NATURAL CAUSES - ASH AND GAS THROWN INTO ATMOSPHERE BY VOLCANOES REFLECT SUN RAYS BACK INTO SPACE - EARTH COOLS - CHANGES IN ORBIT AROUND SUN CAUSE ICE CHANGES
• HUMAN CAUSES - RISING CO2 CAUSES GREENHOUSE EFFECT - SOOT AND GASES PRODUCED BY FACTORIES REFLECT HEAT BACK TO EARTH - INCREASE IN LOCAL TEMPERATURE

POWER (W) = VOLTAGE (V) X CURRENT (A)

• 1 WATT MEANS 1 JOULE PER SECOND
• THE HIGHER THE POWER RATING, THE MORE EXPENSIVE THE DEVICE WILL BE TO RUN

KILOWATT HOUR - AMOUNT OF ELECTRICAL ENERGY CONVERTED BY A 1KW APPLIANCE LEFT ON FOR 1 HOUR

• HIGHER THE POWER RATING OF THE APPLIANCE, THE LONGER YOU LEAVE IT ON, THE MORE ENERGY IT CONSUMES AND THE MORE IT COSTS

ENERGY SUPPLIED (KWH) = POWER (KW) X TIME (H)

COST = NUMBER OF UNITS (KWH)  X PRICE PER UNIT

OFF PEAK ELECTRICITY - ENERGY SUPPLIED DURING THE NIGHT

• ADVANTAGES - COST EFFECTIVE TO ELECTRICITY COMPANY - POWER STATIONS CAN'T BE TURNED OFF AT NIGHT - CHEAPER FOR CONSUMER IF THEY BUY ELECTRICITY DURING HOURS OF LOW DEMAND
• DISADVANTAGES - SLIGHTLY INCREASED RISK OF FIRE - MORE APPLIANCES RUNNING AT NIGHT WITH NO ONE WATCHING - FITTING ROUTINE AROUND OFFPEAK HOURS LIMITS ENJOYMENT DURING DAY

TRANSFORMERS

• FOR POWER TO BE TANSMITTED, A HIGH VOLTAGE OR A HIGH CURRENT IS NEEDED - HIGH CURRENT CAUSES CABLES TO GET TOO HOT WHICH IS INEFFICIENT (ENERGY LOST AS HEAT)
• CHEAPER TO INCREASE VOLTAGE - VOLTAGE TRANSFORMED TO 400 000 V BEFORE BEING SENT ROUND COUNTRY (KEEPS CURRENT VERY LOW) BY STEP UP TRANSFORMER 
• HIGH VOLTAGE IS CHEAPEST WAY TO TRANSMIT ELECTRICITY (EVEN THOUGH PIG PYLONS WITH HUGE INSULATORS AND TRANSFORMER THEMSELVES ARE NEEDED)
• VOLTAGE IS BROUGHT DOWN TO SAFE, USABLE LEVELS FOR HOMES BY LOCAL STEP DOWN TRANSFORMERS IN TOWNS
• TRANSFORMERS ONLY WORK WITH AC - MAIN REASON MAINS ELECTRICITY IS AC

IONISATION - ATOMS LOSING OR GAINING ELECTRONS CAUSING NUCLEUS TO BE UNSTABLE

• RADIOACTIVE MATERIALS GIVE OUT NUCLEAR RADIATION IN FORMS OF ALPHA, BETA AND GAMMA OVER TIME - CAUSES IONISATION OF ATOMS
• POSITIVE IONS FORMED WHEN ATOMS LOSE ELECTRONS, NEGATIVE IONS FORMED WHEN ATOMS GAIN THEM
• IONISATION CAN INITIATE CHEMICAL REACTIONS BETWEEN DIFFERENT ATOMS
• RADIATION ENTERS HUMAN CELLS - CAN IONISE MOLECULES AND DAMAGE DNA - CAUSE MUTATIONS
• HIGH DOSES CAN KILL CELLS COMPLETELY
• IONISING POWER OF EACH KIND OF RADIATION - LINKED TO HOW FAR IT CAN PENETRATE MATERIALS - FIRTHER THE RADIATION CAN PENETRATE BEFORE HITTING AN ATOM, THE LEAST IONISING IT IS

PENETRATING POWER - HELPS IDENTIFY TYPE OF RADIATION

• PLACE MATERIAL BETWEEN RADIATION SOURCE AND DETECTOR (GEIGER COUNTER)
• ALPHA IS STOPPED BY A SHEET OF PAPER
• BETA - STOPPED BY THIN SHEET OF ALUMINIUM 
• GAMMA - STOPPED BY THINK SHEET OF LEAD

ALPHA PARTICLES

• RELATIVELY BIG, HEAVY AND SLOW MOVING - 2 PROTONS AND 2 NEUTRONS
• STOPPED QUICKLY BECAUSE OF SIZE - DON'T PENETRATE PAPER OR SKIN
• STRONGLY IONISING - COLLIDE WITH A LOT OF ATOMS AND KNOCK ELECTRONS OFF BEFORE SLOWING

BETA PARTICLES

• ELECTRONS - SMALL AND QUITE FAST MOVING
• PENETRATE MODERATELY BEFORE COLLIDING - MODERATELY IONISING
• CAN BE STOPPED BY A FEW MILLIMETERS OF ALUMINIUM

GAMMA RAYS

• TYPE OF EM RADIATION - VERY HIGH FREQUENCY - RELEASED WHEN OBJECT HAS EXTRA ENERGY TO GET RID OF AFTER EMITING ALPHA OR BETA PARTICLE
• NO MASS AND NO CHARGE - PENETRATES A LONG WAY - WEAKLY IONISING - PASS THROUGH NOT COLLIDE
• STOPPED BY VERY THICK CONCRETE OR A FEW CM OF LEAD

USES OF RADIATION

• ALPHA - SMOKE DETECTORS - WEAK SORCE OF ALPHA RADIATION CLOSE TO TWO ELECTRODES - RADIATION IONISES AIR AND CURRENT FLOWS BETWEEN ELECTRODES - SMOKE ABSORBS RADIATION SO IF THERES A FIRE, CURRENT STOPS AND ALARM SOUNDS
• BETA - MEDICAL USES - TACERS - RADIOACTIVE SOURCE INJECTED OR SWALLOWED BY PATIENT - PROCESS AROUND BODY CAN BE TRACED USING EXTERNAL RADIATION DETECTOR - COMPUTER CONVERTS READING TO TV DISPLAY SHOWING WHERE STRONGEST READING IS COMING FROM - CAN SHOW WHETHER BODY IS WORKING PROPERLY
• BETA USED BECAUSE IT PASSES OUT OF BODY AND THINGS ONLY RADIOACTIVE FOR A FEW HOURS
• BETA - INDUSTRIAL USES - THICKNESS CONTROL - DIRECT RADIATION THROUGH PAPER BEING MADE AND PUT DETECTOR AT OTHER SIDE - AMOUNT DETECTED DECREASES - PAPER TOO THICK
• RADIOACTIVE SUBSTANCE MUSTN'T DECAY QUICKLY FOR THIS USE - READING SLOWLY  FALL - TOO THICK 
• BETA USED - READING EFFECTED BY THICKNESS - NOT TOO GREATER OR WEAKER PENETRATING POWER
• GAMMA - MEDICAL USES - TREATING CANCER - KILLS ALL LIVING CELLS - DIRECTED CAREFULLY 
• STERILISING MEDICAL EQUIPMENT - KILLS MICROBES - BETTER THAN BOILING - DAMAGES INSTRUMENTS
• USED BECAUSE ITS A STRONGLY RADIOACTIVE SOURCE THAT LASTS A LONG TIME - NO REPLACING
• GAMMA - INDUSTRIAL USES - TESTING AIROPLANE TURBINE BLADES FOR CRACKS

NUCLEAR POWER

• NUCLEAR POWER STATIONS USES NUCLEAR FISSION TO PRODUCE HEAT TO CREATE STEAM
• IN NUCLEAR FISSION, URANIUM ATOMS ARE SPLIT IN TWO, RELEASING LOTS OF HEAT ENERGY
• WATER USED AS COOLANT - TAKES AWAY HEAT PRODUCED BY FISSION PROCESS - HEAT USED TO PRODUCE STEAM TO DRIVE TURBINE AND GENERATOR

NUCLEAR WEAPONS

• USED URANIUM FUEL FROM NUCLEAR POWER STATIONS REPROCESSED - WAY OF DEALING WITH RADIOACTIVE WASTE THAT WOULD OTHERWISE HAVE TO BE STORED
• AFTER REPROCESSING, URANIUM AND PLATONIUM IS LEFT
• REUSE URANIUM IN NUCLEAR POWER STATION
• PLUTANIUM USED TO MAKE NUCLEAR BOMBS

ADVANTAGES

• CAN MAKE LOTS OF ENERGY WITHOUT RELEASING A LOT OF CO2
• NUCLEAR REACTIONS RELEASE A LOT MORE ENERGY THAN CHEMICAL REACTIONS LIKE BURNING - TAKES A LOT LESS URANIUM TO PRODUCE SAME AMOUNT OF POWER AS FOSSIL FUEL
• RELATIVELY CHEAP
• STILL PLENTY OF URANIUM LEFT 

DISADVANTAGES

• EXPENSIVE TO BUILD AND MAINTAIN
• TAKES LONGER TO START UP NUCLEAR POWER STATIONS THAN FOSSIL FUEL POWER STATIONS
• PROCESSING URANIUM BEFORE USE CAUSES POLLUTION
• RISK OF LEAKS OF RADIOACTIVE MATERIALS OR MAJOR DISASTERS LIKE CHERNOBYL DISASTER
• RADIOACTIVE WASTE - DANGEROUS AND DIFFICULT TO REPROCESS OR DISPOSE OF SAFELY
• NUCLEAR POWER STATIONS HAVE TO BE DECOMISSIONED WHEN TO OLD FOR USE - EXPENSIVE
• URANIUM - NON RENEWABLE RECOURCE 

PROTECTION AGAINST RADIOACTIVE MATERIALS

• RADIOACTIVE SOURCES NEED TO BE STORED SAFELY - KEPT IN LABELLED LEAD BOX AND LEFT OUT FOR AS SHORTER TIME AS POSSIBLE TO KEEP EXPOSURE TIME SHORT
• RADIOACTIVE SOURCES NEED TO BE HANDLED WITH TONGS - NEVER ALLOW SKIN CONTACT - KEEP AT ARMS LENGTH AT ALL TIME - KEEP IT POINTING AWAY FROM YOU AND AVOID LOOKING DIRECTLY AT IT
• INDUSTRIAL NUCLEAR WORKERS NEED TO WEAR FULL PROTECTIVE SUITS TO PREVENT TINY RADIOACTIVE PARTICLES BEING BREATHED IN OR LODGING THEMSELVES IN SKIN, FINGERNAILS ETC.
• LEAD LINED SUITS, LEAD OR CONCRETE BARRIERS AND THICK LEAD SCREENS USED TO SHEILD WORKERS FROM GAMMA RAYS IN HIGHLY RADIOACTIVE AREAS
• WORKERS USE REMOTE CONTROL ROBOT ARMS TO CARRY OUT TASKS IN HIGHLY RADIOACTIVE AREAS

DISPOSAL OF RADIOACTIVE WASTE

• LOW LEVEL WASTE - MOST WASTE FROM POWER STATIONS AND HOSPITALS - PAPER, GLOVES, CLOTHING ETC - DESPOSED OF BY BURYING IN SECURE LANDFILL SITES
• HIGH LEVEL WASTE - STAYS RADIOACTIVE FOR TENS OF THOUSANDS OF YEARS - HAS TO BE TREATED VERY CAREFULLY - SEALED IN GLASS BLOCKS WHICH ARE SEALED IN METAL CANISTERS - BURRIED DEEP UNDERGROUND
• DIFFICULT TO FIND SUITABLE PLACES TO BURY HIGH LEVEL WASTE - HAVE TO BE GEOLOCICALLY STABLE - SUDDEN MOVEMENTS IN ROCK COULD DISTURB CANISTERS - CAUSE THEM TO LEAK - IF GET INTO GROUND WATER, COULD INFECT DRINKING WATER
• WHEN APPROPRIATE AREA FOUND, LOCALS OFTEN OBJECT - HIGH LEVEL WASTE MOSTLY KEPT ON SITE
• NOT ALL WASTE HAS TO BE DESPOSED OF - SOME CAN BE REPROCESSED - RECLAIMED USEFUL
• NUCLEAR POWER STATIONS AND REPROCESSING PLANTS SECURE - HAVE HIGH FENCES AND SECURITY CHECKS RUN ON PEOPLE GOING IN AND OUT - COULD BE TARGET FOR TERRORISTS - USE STOLEN RADIOACTIVE MATERIAL TO MAKE DIRTY BOMB OR ATTACK STATION DIRECTLY
• STRICT REGULATIONS ON HOW WASTE DESPOSED OF - COULD CHANGE AS MORE INFORMATION ON RADIOACTIVE MATERIALS AND PROS AND CONS OF DISPOSAL METHODS IS DISCOVERED 

THE SOLAR SYSTEM

• SOLAR SYSTEM - PLANETS, MOONS, ASTROIDS ETC. ORBITING THE SUN IN ELONGATED ELIPSES
• INNER PLANETS - MERCURY, VENUS, EARTH, MARS - PLANETS CLOSEST TO SUN
• ASTROID BELT - RING OF ASTROIDS ORBITING SUN - BETWEEN INNER AND OUTER PLANETS
• OUTER PLANETS - JUPITER, SATURN, URANUS, NEPTUNE
• STARS - HUGE, VERY HOT, FAR AWAY FROM EARTH - GIVE OUT A LOT OF LIGHT - VISIBLE TO NAKED EYE
• PLANETS - SMALLER, NEARER - REFLECT LIGHT FALLING ON THEM - SOME VISIBLE TO NAKED EYE
• MOONS - ORBIT MANY PLANETS - SOME HAVE MULTIPLE - EARTH HAS ONE

GRAVITATIONAL ATTRACTION

• GRAVITATIONAL ATTRACTION - PULLS EVERYTHING IN UNIVERSE TOWARDS EVERYTHING ELSE 
• FORCE OF GRAVITY HUGE BETWEEN STARS AND PLANETS (BIGGER OBJECT, BIGGER PULL) - MAKES PLANETS ORBIT SUN AND MOON ORBIT PLANETS
• PULL OF OBJECT GETS SMALLER THE FURTHER AWAY THE OBJECT IS - EARTH ORBITS SUN ONLY
• EARTH ALREADY MOVING - GRAVITY MAKES MOVING THINGS CHANGE COURSE - CIRCULAR ORBIT
• CIRCULAR MOTION - CAUSED BY A FORCE (PULL) TOWARDS THE CENTRE OF THE CIRCLE - FOR PLANETS THIS IS GRAVITY - FORCE THAT CAUSES CIRCULAR MOTION CALLED CENTREPETAL FORCE

GALAXIES

• SUN - ONE OF THE BILLIONS OF STARS IN MILKY WAY - ABOUT HALF WAY ALONG ONE OF THE SPIRAL ARMS OF MILKY WAY (GALAXY THAT EARTH IS IN)
• DISTANCE BETWEEN NEIGHBORING STARS IN GLAXY - MILLIONS OF TIMES GREATER THAN DISTANCE BETWEEN PLANETS IN SOLAR SYSTEM
• GRAVITY KEEPS STARS IN GALAXY TOGETHER 
• GALAXIES ROTATE - LIKE CATHERINE WHEEL
• MILLIONS OF TIMES FURTHER APART THAN STARS WITHIN A GALAXY
• UNIVERSE HAS BILLIONS OF GALAXIES
• UNIVERSE IS MAINLY EMPTY SPACE - REALLY BIG

LIGHT YEARS - DISTANCE THAT LIGHT TRAVELS THROUGH A VACUUM IN ONE YEAR

• SCIENTISTS USE LIGHTYEARS WHEN TALKING ABOUT OBJECTS IN UNIVERSE E.G. DISTANCES BETWEEN GALAXIES - USING KM GIVES TOO BIGGER NUMBERS
• 1 LIGHT YEAR EQUAL TO 9 460 000 000 000 KM
• CLOEST STAR TO EARTH AFTER SUN IS 40 000 000 000 000 KM AWAY - ABOUT 4.2 LIGHTYEARS

BLACK HOLES - MADE WHEN LARGE STARS EXPLODE

• REALLY BIG STAR USES UP MOST OF IT'S FUEL - SOMETIMES EXPLODES
• CREATES VERY DENSE EXPLOSION - NOTHING CAN ESCAPE IT'S GRAVITATIONAL PULL
• LARGE MASS, SMALL VOLUME AND VERY HIGH DENSITY - LIGHT CAN'T ESCAPE PULL - "BLACK"
• NOT VISIBLE - ASTRONOMERS HAVE TO DETECT THEM IN OTHER WAYS E.G. OBSERVING X RAYS EMITTED BY HOT GASES FROM STARS AS THEY SPIRAL INTO BLACK HOLE

EXPLORING THE SOLAR SYSTEM - MANNED SPACECRAFT

• SOLAR SYSTEM BIG - SENDING MANNED SPACECRAFT TO MARS TAKES YEARS - NEED TO CARRY A LOT OF FUEL - HEAVY AND EXPENSIVE
• DIFFICULT FOR MEN TO KEEP ALIVE AND HEALTHY - WOULD NEED FOOD, WATER, OXYGEN
  • TEMP NEED TO BE REGULATED - KEEP TOXIC GASES OUT
  • SPACECRAFT HAVE TO SHEILD MEN FROM RADIATION IN SPACE
  • LONG PERIODS IN LOW GRAVITY - MUSCLE WASTAGE AND LOSS OF BONE TISSUE
  • PSYCOLOGICALLY STRESSFUL - YEARS IN SMALL SPACE WITH SAME PEOPLE

UNMANNED PROBES - SPACECRAFT CONTAINING INSTRUMENTS TO RECORD FOTTAGE TO SEND BACK 

• FLY-BY MISSIONS SIMPLEST - PROBE PASSES CLOSE BY OBJECT BUT DOESN'T LAND - GATHER DATA ON TEMPERATURE, MAGNETIC AND GRAVITATIONAL FEILDS, RADIOACTIVITY LEVELS ETC.
• SOME DESIGNED TO ENTER PLANETS ATMOSPHERE - BURN UP AFTER DATA COLLECTED AND SENT BACK
• SOME DESIGNED TO LAND ON OTHER PLANETS - CARRY EXPLORATION ROVERS - WANDER ABOUT
• ADVANTAGES:
  • DON'T HAVE TO CARRY FOOD, WATER, OXYGEN AND WITHSTAND CONDITIONS LETHAL TO HUMANS
  • NO HUMANS WEIGHING PROBE DOWN - MORE INSTRUMENTS CAN BE FITTED
  • CHEAPER - CARRY LESS, DON'T HAVE TO COME BACK TO EARTH
  • NO ONE GETS HURT IN UNEXPECTED CRASHES/BURNING
• DISADVANTAGES:
  • CAN'T THINK FOR THEMSELVES - CAN'T OVERCOME SIMPLE POTENTIALLY DISASTEROUS PROBLEMS THAT HUMAN BRAINS HAVE TO CAPACITY TO
  • CAN'T DO MAINTAINANCE AND REPAIRS LIKE PEOPLE

THE MOON - SCIENTISTS THINK IT WAS FORMED FROM ANOTHER PLANET COLLIDING WITH EARTH

• SOON AFTER EARTH FORMED - SMALLER MARS SIZED PLANET CRASHED INTO IT
• IN HEAT OF COLLISION, DENSE IRON CORES OF TWO PLANETS MERGED TO FORM EARTHS CORE
• LESS DENSE MATERIAL EJECTED AS HOT DUST AND ROCKS - ORBITTED AROUND EARTH - EVENTUALLY CAME TOGETHER TO FORM MOON
• EVIDENCE:
  • MOON - LOWER DENSITY THAN EARTH - NO IRON CORE
  • MOON ROCKS CONTAIN FEW SUBSTANCES WHICH EVAPORATE AT LOW TEMPERATURES - MOON FORMED FROM HOT MATERIAL

ASTEROID BELT - BELT OF ASTEROIDS ORBITING BETWEEN MARS AND JUPITER

• ROCKS BETWEEN MARS AND JUPITER DIDN'T FORM PLANET BECAUSE OF JUPITERS STRONG GRAVITATIONAL ATTRACTION
• MILLIONS OF ASTEROIDS (PILES OF RUBBLE AND ROCK) ORBIT SUN BETWEEN ORBITS OF JUPITER AND MARS
• USUALLY STAY IN ORBITS - SOMETIMES COLLIDE - PUSHED AND PULLED INTO DIFFERENT ONES

METEORITES - ROCKS WHICH HAVE CRASHED DOWN TO EARTH

• METEORS - ROCKS OR DUST THAT ENTERS EARTHS ATMOSPHERE - BURN UP AS PASS THROUGH ATMOSPHERE - SHOOTING STARS
• SOMETIMES PART CRASHES TO EARTHS SURFACE AS METEORITE - RARE - CAN CAUSE HAVOC
• START FIRES, THROW HOT DUST AND ROCKS INTO AIR, MAKE CRATERS
• DUST AND SMOKE CAN BLOCK OUT SUN FOR MONTHS - CLIMATE CHANGE - SPECIES EXTINCT
• CAN TELL METEORITES HAVE HIT IN PAST:
  • LAYERS OF UNUSUAL ELEMENTS IN ROCKS - IMPORTED BY ASTEROID
  • SUDDEN CHANGE IN FOSSIL NUMBERS BETWEEN LAYERS OF ROCK - EXTINCTION

COMETS - BALLS OF ROCK, DUST AND ICE THAT ORBIT EARTH IN HIGHLY ELIPTICAL ORBITS

• COME FROM OBJECTS ORBITING SUN WAY BEYOND PLANETS
• COMET APPROACHES SUN - ICE MELTS - BRIGHT TAIL OF GAS AND DEBRIS - CAN BE MILLIONS OF KM LONG - WHAT WE SEE FROM EARTH
• SPEEDS UP AS APPROACHES SUN - MORE GRAVITATIONAL PULL

NEAR-EARTH OBJECTS - ASTROIDS OR COMETS THAT MIGHT BE ON COLLISION COURSE WITH EARTH

• POWERFUL TELESCOPES AND SATELLITES USED TO MONITOR THEM - WHEN OBJECT FOUND, TRAJECTORY CALCULATED TO SEE IF ON COLLISION COURSE WITH EARTH
• SMALL NEOS - BURN UP HARMLESSLY IN ATMOSPHERE - LARGER ONES - CAUSE EXPLOSIONS MORE POWERFUL THAN NUCLEAR WEAPONS
• IF GET WARNING - TRY TO DEFLECT IT BEFORE COLLISION
• EXPLODE BOMB NEAR IT - NUDGE IT OFF COURSE

EVIDENT EXPANSION OF UNIVERSE

• LOOKS LIKE IT'S GETTING BIGGER - GALAXIES MOVING AWAY FROM EACHOTHER - EVIDENCE:
• LIGHT FROM DISTANT GALAXIES RED SHIFTED - 
  • LIGHT FROM DISTANT GALAXIES - FREQUENCIES LOWER THAN SHOULD BE - SHIFTED TOWARDS RED END OF SPECTRUM
  • SAME EFFECT AS CAR HORN SOUNDING LOWER PITCHED WHEN MOVING AWAY - DROPS FREQUENCY
  • MEASUREMENTS OF RED SHIFT - SUGGESTS ALL GALAXIES MOVING AWAY FROM US VERY QUICKLY - SAME IN EVERY DIRECTION
• MORE DISTANT GALAXIES HAVE GREATER RED SHIFTS
  • MORE DISTANT GALAXIES MOVING AWAY FASTER THAN NEARER ONES - WHOLE UNIVERSE EXPANDING

EVIDENT COSMIC BACKGROUND RADIATION

• LOW FREQUENCY MICROWAVE RADIATION COMING FROM ALL DIRECTIONS AND ALL PARTS OF UNIVERSE - COSMIC BACKGROUND RADIATION
• EVIDENCE FOR BIG BANG - UNIVERSE EXPANDS AND COOLS - BACKGROUND RADIATION COOLS AND DROPS FREQUENCY

THE BIG BANG THEORY

• INITIALLY, ALL MATTER IN UNIVERSE OCCUPIED VERY SMALL SPACE - SMALLER THAN PINHEAD - THEN EXPLODED - SPACE STARTED EXPANDING - EXPANSION STILL GOING ON
• LETS US GUESS AGE OF UNIVERSE - RATE OF CURRENT EXPANSION - 14 BILLION YEARS OLD
• HARD TO ESTIMATE - HARD TO TELL WHETHER SPEED OF EXPANSION CHANGED SINCE BIG BANG

ANCIENT GREEK MODEL OF UNIVERSE - GEOCENTRIC

• BELIEVED SUN, MOON, PLANETS AND STARS OBITTED EARTH - GEOCENTRIC MODEL
• ACCEPTED MODEL OF UNIVERSE FROM ACIENT GREEK TIME TO 1500'S

COPERNIAN MODEL - HELIOCENTRIC

• STATES THAT PLANETS ORBIT SUN IN PERFECT CIRCLES - INTRODUCED BY COPERNUS IN 1543 - BOOK SHOWED ASTRONOMICAL OBSERVATIONS WHICH COULD BE EXPLAINED WITHOUT EARTH CENTRE
• EVIDENCE - STARS NEVER MOVED AWAY FROM JUPITER - CARRIED ALONG WITH PLANET - SUGGESTED THEY WERE MOONS - NOT EVERYTHING IN ORBIT AROUND EARTH

GALILEO 

• 1610 - NOTICED THAT VENUS HAD PHASES - DIFFERENT AMOUNT OF PLANET HIT BY SUN AT DIFFERENT TIMES
• IF PTOLEMIC MODEL RIGHT, CHANGES WOULD BE VERY SMALL - VENUS ALWAYS IN FRONT OF SUN
• IF CAPERNICUS MODEL RIGHT, VENUS MOVE IN FRONT OF AND BEHIND SUN - CHANGES BIG - RIGHT
• COPERNICUS IDEAS NOT POPULAR AT TIME - PREVIOUS MODEL BEEN AROUND LONG TIME
• MODEL CONDEMNED BY CHURCH - WENT AGAINST BIBLE - STATED EARTH AT CENTRE OF UNIVERSE
• EVIDENCE OF COPERNICUS MODEL INCREASED WITH TECHNOLOGICAL ADVANCES
• CURRENT MODEL STILL SAYS SUN AT CENTRE BUT THAT PLANET ORBITS ELIPTICAL

• INITIALLY FORM FROM CLOUDS OF DUST AND GAS - FORCE OF GRAVITY MAKES IT SPIRAL TOGETHER TO FORM PROTOSTAR - GRAVITATIONAL ENERGY CONVERTED TO HEAT ENERGY - STAR HEATS UP
• TEMP HIGH ENOUGH - HYDROGEN NUCLEI UNDERGO THERMONUCLEAR FUSION - FORM HELIUM NUCLEI, HEAT, LIGHT - ENTERS STABLE PERIOD (MAIN SEQUENCE) - HEAT CREATED BY NUCLEAR FUSION PROVIDES OUTWARD FORCE TO BALANCE GRAVITY PULLING INWARDS - BILLIONS OF YEARS
• HYDROGEN BEGINS TO RUN OUT - STAR SWELLS INTO RED GIANT - BECOMES RED AS SURFACE COOLS
• SMALL OR MEDIUM SIZED STAR - BECOMES UNSTABLE - EJECTS OUTER LAYER OF DUST AS PLANETARY NEBULA - LEAVES BEHIND HOT, DENSE CORE (WHITE DWARF) - COOLS DOWN AND FADES AWAY
• BIG STARS - RED GIANTS - GLOW BRIGHTLY AGAIN, UNDERGO MORE FUSION, EXPAND AND CONTRACT SEVERAL TIMES - FORM HEAVIER ELEMENTS IN VARIOUS NUCLEAR REACTIONS - EVENTUALLY EXPLODE TO FORM SUPERNOVA 
• EXPLODING SUPERNOVE THROWS OUTER LAYER OF DUST AND GAS INTO SPACE - ERY DENSE CORE (NEUTRON STAR) - IF STAR BIG ENOUGH, IT BECOMES A BLACK HOLE