Week 9

Question 1

When is thermal radiation released

Answer 1

• When matter temp is above zero
• as a result of vibrational and rotational motion
  Emitted radiation is proportional to object temp

Question 2

What is a blackbody

Answer 2

perfect emitter and absorber of radiation

Question 3

What is a diffuse surface

Answer 3

emits radiation in all directions

Question 4

What is a gray surface

Answer 4

emits independent of wavelength (wavelength has no effect on amount of radiation emitted).

Question 5

what can happed to incident radiation on a surface

Answer 5

• reflected
  -Absorbed
  -transmitted

Question 6

What is specular reflection

Answer 6

Angle of incidence is equal to angle of reflection

Question 7

What is diffuse deflection

Answer 7

reflected energy leaves in all directions

Question 8

What is kirchoffs law

Answer 8

emissivity=absorpivity

Question 9

What is the view factor

Answer 9

shows how much radiation comes from a surface and is received from another surface

Question 10

What is the greenhouse effect

Answer 10

Long wavelengths cannot be transmitted by glass, energy becomes trapped and increases the temp.
Earth heats during day, emits radiation at night as infrared.
CO2 and H2O in atmosphere transmit most radiation but absorbs some= increased temp= global warming

Question 11

Effects of global warming

Answer 11

increased flooding due to rising sea levels
Increased droughts in hot countries