Black Body Radiation

• A perfect black body is...


  an object that absorbs all the radiation that hits it.
• Black bodies are also the best _____ of radiation

  emitters
• All objects emit EM radiation because of...

  the energy in their thermal energy stores
• The intensity and distribution of the wavelengths emitted by an object depend on...


  the object's temperature
• Intensity is the

  power per unit area
• As the temperature of an object increases, the intensity of every emitted wavelength...

  increases
• The intensity increases more rapidly for _____ wavelengths


  shorter (this causes the peak wavelength to decrease)

  
• The curves on a black body graph show how...

  the intensity and wavelength distribution of a black body depends on its temperature

  
• What do all bodies (objects) emit and absorb?

  Infrared radiation
• As temperature increases


  The quantity of infrared radiation emitted by an object increases
• Perfect black body


  An object that absorbs all of the radiation that is incident upon it
• A perfect black body reflects or transmits no radiation
• Perfect black body


  • It is a perfect absorber since it absorbs all radiation incident on it
  • A perfect absorber is also a perfect emitter
• As temperature increases


  The wavelength distribution of any emission is dependent on the object's temperature
• For a body at constant temperature, the rates of emission and absorption are the same
• For a body increasing in temperature

  The body is absorbing radiation faster than it is emitting it
• Factors affecting the temperature of the Earth


  • The Earth's rate of absorption and emission of radiation
  • The amount of reflection of radiation into space