The table gives information about some ways of reducing the energy consumption in a house. Installation cost in. Fit a new hot water boiler

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1 ## (a) The table gives information about some ways of reducing the energy consumption in a house. Method of reducing energy consumption Installation cost in Annual saving on energy bills in Fit a new hot water boiler Fit a solar water heater Fit underfloor heating Fit thermostatic radiator valves Which way of reducing energy consumption is most cost effective over a 0-year period? To obtain full marks you must support your answer with calculations. (3) (b) Explain why using an energy-efficient light bulb instead of an ordinary light bulb reduces the amount of carbon dioxide emitted into the atmosphere. (2) (Total 5 marks) Page of 2

2 Q2. Complete the following sentences. A TV set is designed to transfer electrical energy into... energy and... energy. A hair dryer is designed to transfer electrical energy into... energy and... energy. (Total 4 marks) Q3. The diagrams show what happens to each 00 joules of energy from burning coal on an open fire and in a stove. (a) Add the missing figures to the diagrams. (3) Page 2 of 2

3 (b) Which is more efficient, the open fire or the stove? Give a reason for your answer () (Total 4 marks) Q4. (a) The diagram shows hot water being poured into a mug. (i) Complete the sentence by choosing the correct words from the box. Each word may be used once or not at all. air mug table water Heat energy is being transferred from the... to the.... () When will this transfer of heat energy stop?.... () Page 3 of 2

4 (b) In the box are the names of four types of fuel used to heat homes. coal gas oil wood Which one of these types of fuel is renewable? () (c) The diagram shows where heat energy is lost from a house. (i) Complete the sentences by choosing the correct words from the box. Each word may be used once or not at all. conduction conductor convection electric evaporation insulator The amount of heat energy lost through the windows by... can be reduced by using thick curtains. The curtains trap a layer of air and air is a good.... The curtains will also stop... currents pulling cold air into the room through small gaps in the window. (3) Write down one other way of reducing heat loss from a house... () (Total 7 marks) Page 4 of 2

5 Q5. A gas burner is used to heat some water in a pan. Of the energy released by the burning gas by the time the water starts to boil: 60% has been transferred to the water. 20% has been transferred to the surrounding air. 3% has been transferred to the pan. 7% has been transferred to the gas burner itself. (a) Use the above information to complete the pie-chart. (3) (b) Some of the energy released by the burning gas is wasted. (i) What happens to this wasted energy?.... (2) What percentage (%) of the energy from the gas is wasted? Answer:... % () (Total 6 marks) Page 5 of 2

6 Q6. The diagram shows a side view of a double-glazed window. (a) Use each of the terms in the box to explain how heat is lost from inside a house through the window. conduction convection radiation (3) (b) Besides heat, state one other form of energy that passes through double-glazed windows. () (c) Explain why plastic foam cavity wall insulation cuts down energy transfer between warm inner walls and cooler outer walls. (2) Page 6 of 2

7 (d) When it rains the walls and windows of a house get wet. Explain how the drying process can increase the cooling of the house. (2) (Total 8 marks) Q7. The diagram shows a type of electric immersion heater in a hot water tank. These hot water tanks are normally found in airing cupboards. Information on the immersion heater states: 230 V 0 A (a) Immersion heaters for hot water tanks often have a switch on them labelled bath or sink. The bath position of the switch has both parts of the immersion heater elements in the circuit. The sink position has only the short heater element in the circuit. (i) Explain why the hot water outlet is at the top of the tank, and the cold water inlet is at the bottom of the tank.... (2) Explain how the sink position for the immersion heater is able to save energy.... (2) Page 7 of 2

8 (b) The copper tank is surrounded by plastic foam to minimise energy loss. Explain why a pale, shiny surface to the foam also helps to minimise energy loss. (2) (Total 6 marks) Q8. (a) When an electric kettle is switched on it will take a few minutes to boil the water. Once switched off it will gradually cool down. (i) When the kettle is switched on the water heats. Explain how all of the water is heated. The kettle is now switched off and begins to cool. () Describe how heat energy is transferred through the walls of the kettle (2) Describe how the heat energy is transferred from the walls of the kettle (iii) Describe how heat losses from the surface of a metal kettle may be kept small. (4) Page 8 of 2

9 (b) A shiny metal can and a dull black can are filled with the same amounts of cold water. A radiant heater is placed exactly half way between the cans as shown in the diagram below. Two thermometers are used to measure the temperature of the water in each can every minute. (i) Suggest how the temperature of the water in the dull can would be different from the temperature of the water in the shiny can after ten minutes. Explain your answer to part (i). (3) Page 9 of 2

10 (c) The radiant heater was removed and both the cans were filled with the same amount of boiling water, as shown in the diagram below. The temperature was recorded every minute for ten minutes. (i) Suggest how the temperature of the water in the dull can would be different from the temperature of the water in the shiny can after ten minutes. Explain your answer to part (i). (3) (Total 0 marks) Page 0 of 2

11 Q9. The drawing shows parts of a house where it is possible to reduce the amount of energy lost. (a) Give one way in which the amount of energy lost can be reduced from each of the following parts of the house., 2 and (3) (b) Energy consumption can be reduced by using a more efficient boiler or more efficient light bulbs. What is meant by a more efficient light bulb? () (Total 4 marks) Page of 2

12 Q0. The diagram shows four identical pieces of aluminium. Each had been painted with a different type of paint. A drop of water was placed on each and they were then heated by a radiant heater held about one metre above them. (i) Suggest in which order the pieces of aluminium would become dry. first last () Explain why you chose your order. (2) (Total 3 marks) Page 2 of 2

13 M. (a) four calculations correctly shown = = = = 25 accept four final answers only or obvious rejection of solar water heater and underfloor heating, with other two calculations completed any complete calculation correctly shown or showing each saving 0 of all four calculations = mark answers in terms of savings as a percentage of installation cost may score savings mark only hot water boiler correct answers only 2 (b) less electricity / energy to be generated / needed from power stations accept less demand reduction in (fossil) fuels being burnt accept correctly named fuel accept answer in terms of: fewer light bulbs required because they last longer ( mark) less energy used / fuels burnt in production / transport etc. ( mark) ignore reference to CO 2 or global warming ignore reference to conservation of energy [5] M2. light; sound; heat; kinetic/movement for mark each [4] M3. (a) (i) 5* 60* [* if incorrect but >(i) and (i) + = 75 then credit mark] (iii) 25 each for mark 3 Page 3 of 2

14 (b) stove because more of the energy heats up room / heats the room more or less energy escapes up chimney / less energy wasted [Do not allow less waste with the stove] or no un burnt fuel in smoke reason for mark [4] M4. (a) (i) any one from: water to the mug water to the air mug to the air mug to the table both required direction of transfer must be correct when temperatures are the same accept a specific example eg when the temperature of the water and mug are the same accept radiant heat transfer will never stop (b) wood (c) (i) conduction insulator convection accept convection if not given as 3 answer rd any one from: do not accept any rebuilding of house double glazing loft insulation accept roof for loft Page 4 of 2

15 carpets (cavity) wall insulation do not accept closing doors and windows draft excluders foil behind radiators accept blocking chimney paint inside walls white [7] M5. (a) 60% sector correct other two sectors closer to 3:7 than 2:8 or 4:6 sectors correctly labelled (w.r.t rank order of size) each for mark (b) (i) ideas that wasted energy is transferred to surrounding air pan stove is converted to another/correctly named energy form any 2 for mark each for mark [6] M6. (a) (heat) is conducted through the glass the answers must be within the context of the question (heat) passes through glass and air by radiation both glass and air required (heat) crosses the air gap by convection mention of conduction through air is neutral Page 5 of 2

16 (b) any one from light accept sunlight gamma rays X-rays radio accept sound or ir or microwaves or electromagnet waves (c) any two from cuts down convection currents accept stops air moving air pockets trap air (from moving) accept has air pockets do not accept stops heat moving or traps heat foam is a poor conductor air in the foam is a good insulator accept air is a good insulator in air pockets for both marks 2 (d) evaporation (of the water) do not accept rain is cold takes energy from the house accept takes heat away or higher energy molecules leave first [8] M7. (a) (i) the outlet mark hot water rises or floats up do not accept heat rises the inlet mark cold water replacing any drawn off comes in at the bottom and does not mix with hot or cool the hot water do not accept descriptions of a convection current Page 6 of 2

17 only heats top (of tank) or a small volume credit heats less water no mixing occurs with cold because hot water is less dense or water is a poor conductor no mixing because cold water is more dense (b) radiation (losses from tank) do not accept reflection of heat lower from light or white or shiny surfaces credit they are poor radiators for both marks [6] M8. (a) (i) Carries heat up (as convection current) (iii) () By conduction or from molecule to molecule (2) By radiation or as IR Use shiny surface (inside or outside) or small area 2 (b) (i) Rise more quickly Dull surface good absorber (accept attract = absorb if context correct, then penalise spg mark. Shiny surface poor absorber 2 (c) (i) Fall more quickly Dull surface good emitter Shiny surface poor emitter 2 [0] Page 7 of 2

18 M9. (a) insulation allow example e.g fibreglass double glazing allow curtains draught excluder allow double glazing / close fitting door allow turning down thermostat once only / turn down the heating (b) transfers more useful energy allow converts more energy into light / less into heat / less energy wasted [4] M0. (i) D, C or B, in either order, then A tick or cross on the A matt absorbs energy (better than shiny) the converse arguments are acceptable black absorbs energy (better than white) [3] Page 8 of 2

19 E. In part (a) those candidates who chose the payback route generally gained no credit, unless they picked the boiler as the best option. Many candidates scored two marks for selecting the boiler and a correct calculation. A significant number of candidates scored all three marks for completing all the calculations correctly and making the correct choice. Few candidates scored 2 marks in part (b). Most candidates failed to link the less energy back to the power station. The common mark scored was for stating the reduction in fuel burnt. Many considered the efficiency of the bulbs; but did not link it back to the need to generate less electricity. Very few thought about the need for fewer bulbs and the energy saving in their manufacture. There were a significant minority of candidates who thought that conventional light bulbs emit carbon dioxide or that energy loss somehow produces carbon dioxide, often as a result of heat loss. E2. An easy start to the paper. Almost all candidates gained at least some marks, most gaining 3/4 marks. E4. In part (a), the majority of candidates were able to identify from the word box the suitable sources and destinations for the heat energy but only a minority appreciated that heat transfer continues until temperatures become equal. In part (b) wood was generally correctly identified as the renewable type of fuel. The theory and practice of reducing heat energy loss from a house was widely understood. However a significant number of candidates apparently thought that electric currents pull cold air into a room. E5. Part (a) was handled well by most candidates, though neatness and accuracy could have been better. Few candidates were able to explain to where the wasted energy had been transferred except into the air, and hence the answer given to (b) was usually 20% rather than 40%. E6. Foundation Tier Again this was a poorly answered question. In part (a), even those candidates who understood the mechanisms of conduction, convection and radiation failed to apply their knowledge to the situation described in the question. Most candidates were able to pick up a mark in part (b) for mentioning light or sound. In part (c) very few mentioned trapped air in the cavity wall insulation. The cooling effect of evaporation in part (d) appears to be little known. Again, those candidates who mentioned evaporation often failed to relate this knowledge to the particular context of the question. Page 9 of 2

20 Higher Tier Although candidates showed good knowledge of the mechanisms of the three transfer processes in part (a), it was poorly answered in the context of the question. Candidates had considerable trouble expressing themselves coherently. Few attained the radiation mark. There may have been some confusion, since pupils are taught that double glazing reduces heat loss but science must be capable of being applied as well as regurgitated. Some candidates thought the diagram showed a window with an air gap open at the top. Many candidates described convection within the room or radiation from a radiator or from the Sun. Some had warm air going through the glass. A pleasing number of candidates answered part (d) well, though many failed to link energy needed with evaporation. E7. In (a) most candidates failed to attain both marks. Few mentioned hot and cold water would not mix. Candidates tended not to relate their answers to the context. Many stated heat rises, with no integration of science to the situation. In (b) only the most able candidates could explain that pale shiny surfaces minimise energy loss by reducing loss of radiant energy, as they are poor radiators. Weaker candidates focused on the reflective nature of light surfaces. E9. (a) This part was generally well done but weaker candidates gave insulation or double glazing indiscriminately. (b) This was less well answered, with most being in terms of using less energy or lasting longer. E0. Part (a) was generally well answered. Many candidates that failed to achieve on this question were writing about light rather than thermal energy being absorbed or reflected. A worrying number said that black attracts heat. Page 20 of 2

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