1. What energy does the sun emit and what can it be used for?
Light and heat. Used to make electricity.
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2. What type of energy is the sun's?
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3. How do photocells work?
Energy abosrbed by photocell causing electrons to be knocked loose from the silicon atoms in the crystal. Flow freely. Creating a DC current. (Same direction)
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4. What does the power output of photocells depend on?
The surface area that is exposed to sunlight. Intensity of the light. The distance between light source and the photocell.
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5. How do you maximise power output of a photocell?
Track/ Follow the sun in the sky.
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6. What are the advantages of a photocell?
Renewable energy, no need for fuel, no pollution/waste, little maintenance required, long life, operate in remote locations to give access to electricity without power cables.
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7. What are the disadvantages of a photocell?
No power at night/bad weather. Expensive to buy. Take up ablot of space.
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8. What can light be converted into also?
Heat energy. Water passes over this surface to be heated.
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9. What can be used to focus the sun's light?
A curved mirror, like a magnifying glass. Making it more intense.
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10. What does passive solar heating mean/do?
Refers to a device (eg a greenhouse) that traps heat energy but doesnt change it into another form. like conservatories in the summer.
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11. How does passive solar heating work?
Visable light and infrared light passing through glass into a room. Absorbed by objects causing them to heat up. Objects then re-emit infrared of longer wavelength so they cannot escape the room. Heating it up.
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12. What does the sun's energy also create?
Convection currents in the air (wind). Wind Turbines transform the kinetic energy into electrical energy.
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13. What are the advantages of wind turbines?
Renewable, no pollution/waste, it is free after set up costs.
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14. What are the disadvantages of wind turbines?
Require alot of space, dependant on wind (unreliable), visual pollution.
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15. The dynamo effect refers to the way in whcih electricity can be generated by:
moving a wire, or coil of wire near a magnet. Moving a magnet near wire/coil of wire.
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16. What happens in the dynamo effect?
Wire cuts through the lines of force of the magnetic field and a current is produced by electromagnetic induction in the wire. As long as the wire is a full circuit.
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17. How can the current generated increase?
Stronger magnet, more turns in the coil, moving the coil faster, moving the magnet faster.
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18. What happens in a generator?
Coil of wire rotated in a magnetic field. Coil cuts through magnetic field, relative motion causes a current in the coil. Current alternates (changes direction of flow) so a generator produced an alternating current (AC).
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19. Draw a graph of an alternating current.
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20. What is the frequency of an AC generator?
Number of cycles completed each second.
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21. How is electricity produced in power stations?
Fuel burnt, boils water to produce steam, drives turbines, drive generators, produce electricity.
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22. What is the electricity produced in power stations distribed by?
The National Grid.
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23. What happens in each stage of the electricity transfer process?
Energy is transferred to the surroundings in a non-useful form, usually as heat.
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24. How do you work out efficiency?
Efficiency = Electrical energy output (J)/ Fuel energy input x 100.
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25. What is an energy transfer diagram?
Shows how much energy is wasted at each stage.
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26. What do greenshouses gases do?
Trap heat in the atmosphere and warm the earth to support life.
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27. What is happening for the past 50 years?
Global warming.
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28. What revents heat radiating into space?
Most electromagnetic radions can pass through atmosphers, some wavelengths absorbed by gases in atmosphere.
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29. What are the greenhouse gases?
Carbon dioxide, water vapour and methane.
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30. When are these gases produced?
During burning of fuels.
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31. What do some people and other people believe that is causing global warming?
Natural cycles and man activity on earth.
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32. Give some reasons to support the fact that humans are to blame for global warming.
Burning more fossil fuels, amount of carbon dioxide increasing, greenhouse gases trap heat and prevent it from escaping. Average temperature increasing.
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33. Give some reasons to refute the fact that humans are to blame for global warming.
Temperature of the earth changes over time (40000 year cycle). Amount of carbon dioxide not enough to affect global temperatures. Water vapour has a much more significant effect on global warming. Surface temperatures increased on Mercury and Venus.
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34. What does evidence and opinion based mean?
Evidence - Based upon data from scientific experiments or previous studies. Opinion - Not tested scientifically.
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35. What happens before data is universally accepted?
Repeatable by other scientists and verified as accurate.
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36. Why does the greenhouse effect occur and how does it happen?
Short wavelengths from sun absorbed by earth. Radiates as longer wavelengths infrared. Gases abosrb some of these longer wavelengths warming the atmosphere.
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37. Give examples of fossil fuels and the method of releasing energy.
Crude oil, coal, natural gas. Fuel burnt to release energy.
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38. Give examples of biomass and the method of releasing energy.
Wood, Straw, Manure. Fermented to generate methane.
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39. Give examples of Nuclear Fuel and the method of releasing energy.
Uranium. Fuel rods to release energy.
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40. What voltage is the electricity supplied at by the National Grid?
40000 volts.
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41. What are transformers?
Increase and decrease the voltage before and after transmission. Voltage too high for consumers so transformers used to reduce the voltage to safe use. (Step-down transformer)
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42. How is an electric currrent transmitted along a wire?
The wire heats up due to collisions within the material. Wire looses heat the environment.
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43. If electricity is transmitted at a higher voltage (power the same) the current...
in the wire is reduced. Lower current means less heating of the wire so less energy lost.
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44. What is offpeak electricity?
Electricity during the night-time period. Off-peak rate for 7 hours a night. Economy-7.
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45. What are the advantages and disadvantages of off-peak electricity?
A) Less demand for electricity at night. Cheaper electricity for consumer. Avoids wasting electrical costs. D) Inconvinient to run appliances at night because of the noise they make.
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46. What are the advantages of fossil fuels?
Cheep and easy to obtain. Enough reserves - short to medium term. Flexible in meeting demand. Doesnt produce SO2
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47. What are the disadvantages of fossil fuels?
Produces CO2, global warming and acid rain. Removing SO2 from the products adds to cost. Oil spillage during travel. Expensive pipelines for transportation.
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48. What are the advantages of biomass?
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49. What are the disadvantages of biomass?
CO2 and SO2. Large areas needed to grow trees.
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50. What are the advantages of nuclear fuels?
Cost and rate of production low. Sparsely populated areas. Flexible in meeting demand. No CO2 or SO2. High stocks of nuclear fuel. Reduce use of fossil fuels.
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51. What are the disadvantages of nuclear fuels?
Stay dangerous for thousands of years. Stroring waste is expensive. Building and recommisioning cost high. Long start up time. Risk of release of radioactive material. High maintenence costs.
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52. What are the advantages of renewable energy?
Clean, constructed in remote areas, no fuel costs, no chemical pollution, low maintenance, no global warming.
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53. What are the disadvantages of renewable energy?
Produce small amounts of energy (apart from hydroelectric), take up alot of space, visual pollution, unreliable dependant on weather mostly. Cannot guarentee supply on demand. High intial capital outlay.
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Card 2


2. What type of energy is the sun's?



Card 3


3. How do photocells work?


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Card 4


4. What does the power output of photocells depend on?


Preview of the front of card 4

Card 5


5. How do you maximise power output of a photocell?


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