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3 Methods of Heat Transfer Nothing in the textbook! Heat Transfer Lesson aims: To understand CONDUCTION, CONVECTION and RADIATION. Conduction 1. Listen once. 2. Listen again, take notes. 3. Construct an explanation with a partner. Conduction (only occurs in solids) • Hot particles vibrate a lot • Cool particles vibrate a little Conduction • Fast-moving particle (lots of energy) collide with neighbouring particles • This gives them more energy, making them vibrate faster Conduction • This continues along the length of the solid until all the particles are vibrating with lots of energy Conduction 1. Listen once. 2. Listen again, take notes. 3. Construct an explanation with a partner. Conduction (mainly occurs in solids) • Hot particles vibrate a lot • Cool particles vibrate a little Conduction • Fast-moving particle (lots of energy) collide with neighbouring particles • This gives them more energy, making them vibrate faster Conduction • This continues along the length of the solid until all the particles are vibrating with lots of energy Conduction 1. 2. 3. 4. Listen once. Listen again, take notes. Construct an explanation with a partner. Now check! Conduction (only occurs in solids) • Hot particles vibrate a lot • Cool particles vibrate a little Conduction • Fast-moving particle (lots of energy) collide with neighbouring particles • This gives them more energy, making them vibrate faster Conduction • This continues along the length of the solid until all the particles are vibrating with lots of energy Another demo… Conduction Investigation Investigation: Which substance is the best conductor? brass iron glass Predict, in your books, which material you think will be the best CONDUCTOR, and which the best INSULATOR. Conduction Investigation How do you think this experiment works? Conduction Investigation Conclusion: Brass is the best conductor, glass is the best insulator (or worst conductor). This is because the bonds between the atoms in metals are not as strong as in glass (nonmetals). Therefore, the particles are better able to vibrate and transfer heat energy. Heat Transfer Lesson aims: To understand CONDUCTION, CONVECTION and RADIATION. Convection Demonstration How does this happen? Convection Investigation What will happen when purple dye is put in a beaker, and the water is heated? Set it up and try. A CONVECTION CURRENT is created. Why do some objects FLOAT or SINK?? What do you remember about density? Convection (only occurs in fluids) • A fluid is a liquid or a gas • One part of the fluid gets heated – the particles move around with more energy •“Hot” particles are more spaced out so they are less dense, and rise •“Cool” particles or closer together so they are more dense, and fall A better demonstration of this… Now… Find the steps of the creation of a CONVECTION CURRENT and put them in order. You are allowed to write down NUMBERS ONLY!! (They may be around the room or outside…) The process… D. Particles are heated up. B. The particles with more energy move around more. F. The faster moving particles take up more space. C. Their density is lower. E. The lower density fluid rises. G. This pushes the cooler fluid down. A. A convection current is created. Heat Transfer Lesson aims: To understand CONDUCTION, CONVECTION and RADIATION. How does… energy reach us from the sun?? Radiation • When heat is moved from one place to another without using particles, it is called radiation • Heat radiation is infrared energy waves Radiation • These energy waves can travel through any type of material but can be blocked by anything that is too thick or dense • Heat radiation can travel through a vacuum – this is how the heat from the Sun reaches us How else can thermal energy move? • All objects transfer thermal energy by infrared radiation. • The hotter an object is, the more infrared radiation it gives off. Radiation • No particles are involved in radiation, unlike conduction and convection. • This means that thermal energy transfer by radiation can even work in space, but conduction and convection cannot. Radiation Investigation Put 100ml of water into cans of different colours. Put a lamp close to the cans. Measure the temperature every minute. Conclusion The dark cans gained the most heat, whereas the metallic cans gained the least. This is because the shiny and light coloured surfaces reflect the radiated heat from the lamp. However, the dull and dark surfaces absorbed the heat. Radiation Investigation II Repeat the same investigation, but with hot water (and no light). HYPOTHESIS? BONUS ACTIVITY! Thermos Flasks… Does anyone have one of these? What is it used for? BUT HOW??! Thermos flasks… In your group, explain what is going on! Think about how CONVECTION, CONDUCTION and RADIATION are being reduced… Tight fitting insulated bottle cap (lid) Tight fitting so that there’s less (almost none) heat transfer by convection Insulated so that there’s hardly any heat transfer by conduction Glass bottle or stainless steel (unbreakable ?) with hollow container walls and no particles inside i.e. vacuum - So no heat transfer by conduction or convection Silvered (bright and shiny) inside and outside covering this limits the amount of heat transfer (absorption and emission) by radiation Insulated placers to keep the bottle safely and firmly in place, and away from the outside wall of the container Thermos lid/cup Heat Transfer Lesson aims: To understand CONDUCTION, CONVECTION and RADIATION. BONUS ACTIVITY 2! BIG HEAT TRANSFER QUIZ Answers on your whiteboards… Q: Heat is a form of.. A: Energy . Q: Heat will travel along this rod by... A: Conduction Q: Heat can travel through space by the process of ... A: Radiation Q: A material which does not conduct heat is called an... A: Insulation Q: There are no particles in space, it is a... A: Vacuum Q: Which colour of t shirt would absorb heat best? A: Black Q: When particles are heated they... A: Rise Q: Heat can travel through metals by conduction so they are called.... A: Conductors Q: When particles in a metal are heated they start to more A: Vibrate Q: Heat can only travel by convection in a or A: Liquid or Gas Q: Which colour of teapot would keep your tea hotter for longer? A: Silver Heat Transfer Lesson aims: To understand CONDUCTION, CONVECTION and RADIATION. Energy Sources Lesson aims: To know how the world meets its energy needs. To consider how energy production may change in the future. Energy Sources Task: A case study on a country’s energy production Research a country’s method of creating electricity. Go to the following page for information on the task requirements (1 period only). www.bit.ly/energyresourceposter You will be given a country at random… The COUNTRIES: 1. 2. 3. 4. 5. 6. 7. 8. Sweden UK Brazil Argentina Vietnam China Japan France 9. Australia 10.Thailand 11.USA 12.Germany 13.Denmark 14.Egypt 15.Canada Market Place Activity 1. One of you will present the information on your poster. 2. The other will go and find out about other countries. 3. Make notes and record information to share with your partner. 4. Swap roles after 3 countries. 5. Return to your seat. 6. Complete notes on 3 countries. GO!!