1. APHY201 3/18/2016 1 14.6 Conduction   An exchange of kinetic energy between particles. How do the particles interact?   The vibrational state of the atoms and the motion of free electrons determines the level of conductivity in a substance. Metals are the best, gases are the worst. Why?

2. APHY201 3/18/2016 2 14.6 Conduction Rate of energy transfer

3. APHY201 3/18/2016 3 14.6 Conduction Insulation and R value

4. APHY201 3/18/2016 4 14.7 Convection   Energy transfer by the movement of a substance   Examples: heating water, heating/cooling our homes, cloud formation, cooling our bodies, Sun (Movie 1, 2)12

5. APHY201 3/18/2016 5 14.8 Radiation   Energy transfer by electromagnetic waves Needs no material like conduction or convection

6. APHY201 3/18/2016 6 14.8 Radiation   The Earth receives 1350 W/m 2 at upper atmosphere

7. APHY201 3/18/2016 7 14.8 Radiation

8. APHY201 3/18/2016 8 14.8 Radiation   Earth’s peak output is IR → greenhouse effect

9. APHY201 3/18/2016 9 14.8 Radiation UV Visible IR

10. APHY201 3/18/2016 10 In class: Problems 36, 60 Other problems ↓ 40. (a) The cross-sectional area of the Earth, perpendicular to the Sun, is Why is this not an accurate value for the rate of energy received by the Earth?