1. Thermal Energy Transfer
Unit 6: Thermal Energy

2. Review What is the difference between temperature and heat?
Temperature is the measure of the average kinetic energy of the particles in an object
Heat is the transfer of energy between object due to a difference in temperature

3. Review In what direction does heat ALWAYS flow?
From areas of higher temperature to areas of lower temperature

4. Thermal Energy Transfer
Thermal energy transfer will travel from objects or locations at higher temperature to objects or locations at lower temperature
REMEMBER: during energy transfers, the law of conservation of energy is always observed
Energy cannot be created or destroyed: only transformed

5. Thermal Energy Transfer
Three types of thermal energy transfer:
Conduction
Convection
Radiation

6. Conduction
Conduction is the transfer of energy through matter by direct contact between particles
Usually occurs between solids

7. Conduction
For conduction to work, the materials must be:
In direct contact with each other
At different temperatures

8. Conduction
Heat is transferred from one particle to the next as each particle vibrates more quickly

9. Convection
Convection is the transfer of energy through the movement of matter
Convection only occurs in FLUIDS (liquids or gases)

10. Radiation
Radiation is energy transfer through electromagnetic waves that do not require matter (a medium)
Examples: sunlight, space heater, microwave oven

11. Label the following diagram with the terms conduction, convection, and radiation

12. Conductors and Insulators
Conductors are any material through which energy is easily transferred
Examples: metals and waters

13. Conductors and Insulators
Insulators slow down energy transfer and are poor conductors
Examples: oven mitts, rubber, plastics, styrofoam

14. The Rate of Thermal Energy Transfer
The rate at which thermal energy is absorbed or emitted depends on the object’s:
Color
Starting temperature
Texture
Exposed surface area

15. The Rate of Thermal Energy Transfer
If all other conditions are kept equal, in a given amount of time, black rough surfaces absorb more thermal energy than smooth white surfaces

16. The Rate of Thermal Energy Transfer
White surfaces reflect all colors of white light
Black surfaces absorb all colors of white light
It will make sense that, if the black surfaces are absorbing more light than the white surfaces, the black surfaces also absorb more heat