Living for the Future

1. Living for the Future (OCR Gateway Additional Science) W Richards

2. P2a Collecting Energy from the Sun

3. Solar Panels and Thermal Towers What are the advantages and disadvantages of solar power?

4. Using Solar Energy in remote places

5. Solar Energy Solar panels – convert sunlight directly into ______. Sunlight knocks ______ loose from the crystal structure and the loose electrons form a DC electric ______. The amount of power depends on the ___ of the panel and the light ______ and the distance to the ____. Words – current, electricity, electrons, sun, area, intensity

6. Other ways to use solar energy Heating for homes – these pipes carry water that absorbs heat energy and transfers it to the house. Using curved mirrors and solar panels – these curved mirrors focus light onto a chosen point and efficient ones can track the sun across the sky Wind power – heat from the sun causes convection currents which then form wind. What are the advantages and disadvantages of wind power?

7. Passive solar heating “Passive solar heating” is the idea of using solar power to heat homes. Here’s how they work: • Glass is transparent to the sun’s radiation • The “thermal mass” next to the glass absorbs the sun’s heat energy • The surface then emits radiation of longer wavelength • The glass helps reflect the infra red back inside the house

8. P2b Generating Electricity

9. DC and AC 02/01/2020 02/01/2020 V DC stands for “Direct Current” – the current only flows in one direction. Batteries supply DC. Time 1/50th s AC stands for “Alternating Current” – the current changes direction 50 times every second (frequency = 50Hz). Household electricity is AC 230V T V

10. 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

11. AC Generator 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

12. Using non-renewable fuels in power stations 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 the electricity is sent into the National Grid

13. Efficiency Efficiency = Useful energy out Energy in x100% 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 (?)

14. Some examples of efficiency… • 5000J 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 240J 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?

15. Efficiency of Power Stations Heat Heat Heat 15J Boiler Turbine Generator 100J 50J 5J 85J 35J 30J Heat Kinetic Electrical What is the efficiency at each stage of this power station?

16. P2c Global Warming The following two graphs are taken from Wikipedia. What do they imply?

17. 02/01/2020

18. 02/01/2020

19. The Greenhouse Effect We get heat from the sun: • Here’s how the greenhouse effect works: • Our atmosphere absorbs a lot of infra red ________ from the sun • Short wavelength EM radiation from the sun is absorbed by the _______ and heats it up • The Earth re-radiates heat as _______ wavelength EM radiation (i.e. _______ _____) • Greenhouse gases such as _____, carbon dioxide and water vapour absorb some of this infra red and re-radiate it back to the Earth causing it to ______ up. Words – longer, radiation, Earth, warm, infra red, atmosphere

20. The Changing Greenhouse Effect Deforestation Volcanoes Factory pollution The Greenhouse Effect has been around for millions of years but scientists are concerned that it has been increasing in recent decades. How have the following things affected this?

21. Differing views on Global Warming The following data shows global warming figures and projections from different research centres. What do you notice?

22. P2d Fuels for Power

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

24. Nuclear power stations The main difference is that the nuclear fuel (uranium) is NOT burnt – it is used to boil water in a “heat exchanger” These work in a similar way to normal power stations:

25. Biomass 02/01/2020 “Biomass” is a term used to describe anything that can be grown or biologically made and then burned as a fuel:

26. Non-renewable energy sources Coal, oil, gas and nuclear Advantages Disadvantages Cheap fuel costs Costs a lot of money to decommission a nuclear plant Good for “basic demand” 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

27. Renewable energy sources summary Wind, tidal, hydroelectric and solar Advantages Disadvantages Zero fuel costs Unreliable (except for hydroelectric) Don’t produce pollution 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)

28. Energy and Power E P T The POWER RATING of an appliance is simply how much energy it uses every second. In other words, 1 Watt = 1 Joule per second E = Energy (in joules) P = Power (in watts) T = Time (in seconds)

29. Some example questions • What is the power rating of a light bulb that transfers 120 joules of energy in 2 seconds? • What is the power of an electric fire that transfers 10,000J of energy in 5 seconds? • Rob runs up the stairs in 5 seconds. If he transfers 1,000,000J of energy in this time what is his power rating? • How much energy does a 150W light bulb transfer in a) one second, b) one minute? • Jonny’s brain needs energy supplied to it at a rate of 40W. How much energy does it need during a 50 minute physics lesson? • Lloyd’s brain, being more intelligent, only needs energy at a rate of about 20W. How much energy would his brain use in a normal day? 60W 2KW 0.2MW 150J, 9KJ 120KJ 630MJ

30. The Cost of Electricity 02/01/2020 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 A 200W TV left on for 5 hours uses __kWh A 2kW kettle left on for 15 minutes uses __kWh Electricity is measured in units called “kilowatt hours” (kWh). For example…

31. The Cost of Electricity 02/01/2020 To work out how much a device costs we do the following: Cost of electricity=Power (kW)xtime (h)xcost per kWh (p) For example, if electricity costs 12p 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 72p 12p 12p 6p Electricity is cheaper at night time (around 5p per unit) – how much would these devices cost at night time?

32. Power 02/01/2020 P V I Power is “the rate of doing work”. The amount of power being used in an electrical circuit is given by: Power = voltage x current in W in V in A • We can use this equation to analyse power stations: • A transformer gives out 10A at a voltage of 50V. What is its power output? • An electric fire has a power rating of 2KW. If it runs on a voltage of 230V what is the current? • Electricity is transmitted along some lines in the National Grid at 400KV. If the current is 1KA what would be the power through the wire? 500W 8.7A 400MW

33. The National Grid 02/01/2020 Step up transformer Step down transformer Homes Power station Electricity reaches our homes from power stations through the National Grid: If electricity companies transmitted electricity at 240 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 ____. Words – step down, high, power, low, high

34. P2e Nuclear Radiations

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

36. Introduction to Radioactivity 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 “radioactive decay”.

37. Background Radiation 13% are man-made Radon gas Food Cosmic rays Gamma rays Medical Nuclear power

38. Blocking Radiation    Each type of radiation can be blocked by different materials: Sheet of paper Few mm of aluminium Few cm of lead

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

40. Uses of Alpha Radiation Alpha emitter +ve electrode -ve electrode If smoke enters here a current no longer flows Ionised air particles Smoke detectors Alarm

41. Uses of Beta Radiation Beta detector Paper Rollers Beta emitter

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

43. Other uses of radioactivity Gamma source 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: 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:

44. Handling Radioactive Materials Safety measures: • Keep your distance • Minimise exposure time • Protective clothing • Careful labelling Plutonium is a waste product from nuclear power stations and can be used to make nuclear bombs. It remains radioactive for a long time and can be a terrorist risk.

45. Disposing of radioactive waste The containers are then kept in stores, often _________. 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: High level waste is immobilised by mixing with ____ making ingredients, melting and pouring the glass into steel containers. Intermediate waste is set in cement in _____ drums. Words – glass, steel, underground, radioactive

46. P2f Exploring our Solar System

47. The Solar System summarised What makes up our solar system? Complete the following mind map with what you now about each object: The solar system

48. The eight planets of our Solar System Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune As well as the eight planets, the solar system is also made up of asteroids, dwarf planets, comets and moons

49. Distances in space Definition – a “light year” is the distance covered by light every year The Sun, our closest star, is 1.6x10-5 light years away from us. The next closest star, Proxima Centauri (4.2 light years away) The centre of our galaxy, the Milky Way, is around 26,000 light years away. The Andromeda Galaxy (our closest galaxy) – approximately 2.5 million light years away

50. Solar systems, galaxies and the Universe Our planet (around 13,000km diameter and 4500 million years old) is pretty small compared to... OUR SUN (100 times wider and 4.6 billion years old), which is small compared to… THE MILKY WAY, which contains at least 200 billion stars and is 100,000 light years across, which is small compared to… THE UNIVERSE, which contains billions of galaxies and is 14,000 million years old.