1. Heat Transfer Conduction, Convection and Radiation

2. Thermal Energy Transfer
Heat ALWAYS moves from warmer to cooler
There always has to be a temperature difference
The greater the difference in temperature, the faster energy flows

3. How is Heat Transferred?
There are THREE ways heat can move.
Conduction
Convection
Radiation

4. CONDUCTION Definition: Energy is transferred by direct contact.
Conduction = touchin’

5. Conduction
When you heat a metal strip at one end, the heat travels to the other end.
As you heat the metal, the particles vibrate, these vibrations make the adjacent particles vibrate, and so on and so on, the vibrations are passed along the metal and so is the heat. We call this?
Conduction

6. EXAMPLES OF CONDUCTION
A piece of cheese melts as heat is transferred from the meat to the cheese (Contact)
Washing your hands
Feet touching hot sand.

7. CONVECTION Convection = VENTS (through air and liquid particles)
Definition: Energy is transferred in a circular movement within fluids (liquids and gases)
Convection = VENTS (through air and liquid particles)
Convection moves in
a circular pattern

8. Water movement Cools at the surface Convection current Hot water rises
Cooler water sinks

9. Examples of Convection:
Have you ever noticed that the air near the ceiling is warmer than the air near the floor? Or that water in a pool is cooler at the deep end?
Examples:
When the water at the bottom of a pot is heated, its particles move faster, and they also move farther apart. As a result, the heated water becomes less dense. A less dense fluid will float on top of a more dense one. Therefore, the heated water rises in the pot. The surrounding cooler water flows into its place.
This flow creates the circular motion as seen on the next page, which is known as convection currents.
air movement in a home
- pot of heating water.

10. Why is it windy at the seaside?

11. Explaining Convection…
Convection currents cause the cooler breezes you experience by a large body of water.
These currents also cause the movement of magma within the earth.
Explaining Convection…

12. The third method of heat transfer
How does heat energy get from the Sun to the Earth?
There are no particles between the Sun and the Earth so it CANNOT travel by conduction or by convection.
RADIATION ?

13. (heat escaping the sun)
RADIATION
Definition: Transfer of energy by electromagnetic waves
Radiation = Radiates
(heat escaping the sun)

14. Examples of RADIATION
Fire
Heat Lamps
Sun

15. Examples of Radiation
Have you ever sat too close to a campfire while cooking marshmallows? You’re enjoying the warmth ….. only to notice that your skin is really warm?

16. 1. Which of the following is not a method of heat transfer?
A. Radiation
B. Insulation
C. Conduction
D. Convection

17. 2. In which of the following are the particles closest together?
A. Solid
B. Liquid
C. Gas
D. Fluid

18. 3. How does heat energy reach the Earth from the Sun?
A. Radiation
B. Conduction
C. Convection
D. Insulation

19. 4. Which is the best surface for reflecting heat radiation?
A. Shiny white
B. Dull white
C. Shiny black
D. Dull black

20. 5. Which is the best surface for absorbing heat radiation?
A. Shiny white
B. Dull white
C. Shiny black
D. Dull black