Section 10.2

1. Section 10.2 Energy Transfer

2. Methods of Energy Transfer There are 3 methods of energy transfer. • Conduction • Convection • Radiation

3. Conduction • When objects are in contact and there is transfer of heat energy.

4. Convection • This results from the movement of warm fluids (liquids or gas) • The cycle of a heated fluid that rises and then cools and falls is called convective current.

5. Convection current • The cycle in which the flow of the fluid is due to heated expansion followed by cooling and contraction.

6. Radiation • Radiation does not require physical contact between objects. • Electromagnetic waves include: infrared radiation, visible light and ultraviolet rays.

7. Radiation • Radiation is different from conduction and convection because it does not involve the movement of matter. • Radiation is the only method of energy transfer that can take place in a vacuum, ex. outer space.

8. Conductors and Insulators Energy is transferred as heat quickly in conductors. • Conductor: Def. p.334. • Metals are good conductors of heat because energy passes through it easily and quickly.

9. Non metals are not good conductors. • The state of matter (solid, liquid or gas) determines if it is a good conductor too.

10. Insulators Insulators slow the transfer of energy as heat. • Poor conductors of heat and electricity • We use insulators to stop or reduce unwanted energy transfer, ex. wooden spoon.

11. Specific Heat • energy in Joules required to raise an object’s temperature by 1 Kelvin. • Symbolized by the letter c • Specific heat is a physical property. • The unit for Specific heat is J/kg.K • Specific heat equation p.337.