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HEAT TRANSFER: CONDUCTION. DUNMAN SECONDARY SCHOOL Science (Physics). Some Expectations. Respect Others Respect the School Humility. Work Ethic. DO participate and ask questions. For order in class, raise your hand when asking a question. BRING all specified books.
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HEAT TRANSFER: CONDUCTION DUNMAN SECONDARY SCHOOL Science (Physics)
Some Expectations • Respect Others • Respect the School • Humility
Work Ethic • DO participate and ask questions. For order in class, raise your hand when asking a question. • BRING all specified books. • HAND IN all homework ON TIME! Failure to do so may result in consequences… (“Drink coffee” with Mr. Chew after school) • SHOW CARE and concern for each other. Help one another in homework. BUT NO COPYING OF ENTIRE ASSIGNMENTS!
Why learn heat transfer? • Many applications in real life. Example: Making of engines, refrigerators, air cooling systems…
SOLDIER OF TOMORROW • Soldier suits can regulate temperature!!
CHALLENGE!! How do you place a piece of paper over a candle flame without the paper catching fire?
CONDUCTION • Conduction is the transfer of thermal energy without any flow of the material medium. • This is the main process by which thermal energy is transferred from one of the solid to another.
CONDUCTION can occur by Molecular Vibration Free Electron Diffusion
Molecular Vibration • Demonstration of molecular vibration. • What do you observe about the rate of transfer? • A slow process…
Test Your Understanding • Why are gases and liquids generally poor conductors of heat? http://www.cartoonclipart.com/pages/girlread.html
Insulators and Conductors • Poor conductors are also called insulators. Some examples: Water, Wood, Polystyrene.
Free Electron Transfer • METALS contain many free electrons. • See Demostration • Rate of heat transfer is now faster. Why?
Free Electron Diffusion • When heated, the free electrons move faster and diffuse to into the cooler parts of the metal. • Kinetic energy is then transferred to the molecules by collision.
Test Your Understanding • Why is copper a better conductor of heat than wood?
Your research • What are some applications of: • Conductors • Insulators in everyday life? (Choose one) • Do in groups of two or three.
Your Research • Presentation format – YOU DECIDE • Concept Maps with Pictures? • Short video? (Takes a long time… but if you can… why not?) • Research Paper?? (you sure???) • The point is: BE INNOVATIVE • Dateline: 20 Mar 2006 (Mon) 1300 hrs
What we have learnt… • The main process by which thermal energy is transferred from one end of a solid to another is conduction. • Two mechanisms of conduction: • Molecular vibration • Free electron diffusion Done by: Chew Yiming Clement