1. Electromagnetic Waves with Wavelengths
1 nm = 1 x 10-9 meters

2. How electromagnetic waves interact with materials:
Refracted: bent as they pass through materials due to differences in density

3. How electromagnetic waves interact with materials:
Reflected: Bounced off materials

4. How electromagnetic waves interact with materials:
absorbed: Taken in by the material

5. How electromagnetic waves interact with materials:
Transmitted: pass through the material
Scattered: reflected and refracted in various directions

6. Dark materials: absorb more light.
This is why dark-colored asphalt feels hotter in the summer than light –colored concrete
However, they also cool down faster (radiate heat)

7. Light materials absorb less light (and feel cooler) because they reflect back more heat energy

8. Smooth textures absorb less energy and reflect more light
Rough textures absorb more energy because they reflect less light

9. Transfer of Energy
Energy moves from areas of high concentration (a SOURCE) to areas of low concentration (a SINK).
Heat, (a form of energy) moves from areas of high temperature to areas of low temperature
Heat always moves from a source to a sink until the temperatures are equal.
This is a dynamic EQUILIBRIUM

10. sink
source

11. How is Heat transferred?
1. CONVECTION:
Heat is transferred by the movement of FLUIDS (gases or liquids) due to differences in density
Warm fluids have lower density (tend to rise)
Cold fluids have higher density (tend to sink)
This causes convection currents

12. Most people’s homes are heated by convection
It is always the hot fluid that rises, why?

13. (definition)

14. 2. Conduction
Heat is transferred from atom to atom when vibrating atoms collide.
Conduction works best in solids, especially metals and rocks, where atoms are close together

15. 3. Radiation Heat is transferred by electromagnetic waves (light)
Radiation is the fastest of the 3 methods
Radiation can travel through transparent solids, liquids or gases, or even through empty space (vacuum)
Emits all forms of
Electromagnetic waves
Emits light and
Infrared waves

16. This pot of boiling water over a campfire illustrates the 3 methods* * *

17. Transformation of Energy
Kinetic = energy of motion
Potential = stored energy, energy of position due to gravity

18. FRICTION causes energy to be transferred:
A glacier transfers energy of motion into heat energy due to friction against the rock

19. Heat vs.Temperature What is Heat? Units = calories
What is Temperature?
Units = degrees Celsius

20. 1400 degrees
Bonfire
Which has more heat?
Match
1400 degrees

21. Which has more heat, the pool water or the tea? 24 Deg. C
Hot tea (94 deg.C)

22. Temperature
is the measure of the average kinetic energy (the motion) of the particles in a sample
High temp = particles are moving fast
Low temp = particles are moving slowly

23. Heat
Is the sum total of the kinetic energy of the particles in a sample
Bigger sample = holds more heat
Smaller sample = holds less heat