Insulating HousesWhen you sit your exam, they may ask you questions about how homes keep in their heat energy or how it is lost. You should be able to mention different ways in which heat is lost in a home and how they can be reduced. The best way to revise this is by drawing a house then labelling all the places where heat can be lost.
Through an infrared camera, you can see where heat is lost the most. Where is the most heat lost here? QUESTION TIME
(a) The diagram shows the position of a radiator inside a room. The radiator is made from metal and is painted white. (a) (i) Heat is transferred from the hot water inside the metal radiator to the air touching the
outside surface of the radiator. What name is given to this method of heat transfer? (1 mark) (a) (ii) Explain, in terms of the particles in the metal, how heat is transferred through the radiator. (2 marks) (a) (iii) What name is given to the main method by which heat is transferred from the radiator to the people on the other side of the room? (2 marks) (b) A student investigated the effect of shape and colour on heat transfer. The student used metal containers with the same volume but with different shapes and outside colour. The containers were each filled with water at 100 °C. After 20 minutes the temperature of the water inside each container was measured. (Click to enlarge) Their results were given in this table
(i) The student uses the results in the table to see if shape has affected heat transfer.
Which containers should the student compare to do this? Give a reason for your answer.(1 mark) (b) (ii) Explain why the temperature of the water in both containers A and B fell by the same amount. (2 marks) (b) (iii) A central heating system has several radiators joined together. The hot water goes from the boiler, through each radiator in turn and then back to the boiler for reheating. Give one reason, other than appearance, why it might not be a good idea to paint radiators black. (1 mark) |
Heat can be lost:
- through the gaps between the doors - through the windows - through the roof - through the floor - through the walls Through walls, roof, windows and floors heat is lost through conduction. It is transferred by homes through convection. Through the gaps between doors, there is air (which is a fluid) therefore heat can be transferred. Heat can also be lost through walls, windows and through the roof by radiation. Along with complaining about how heat is lost, you must also know methods by which energy loss can be REDUCED. I've made a lovely table to set things out nice and clearly for you. You may thank me later. Click on the pictures to enlarge them. Note: You shouldn't try to remember everything said in the videos. They just help you understand what it's all about :) Mark Scheme for questions. (click to enlarge)
Here's something to just watch :)
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