Black Body Radiation

• Black body


  An object that absorbs all of the radiation that is incident upon it
• All bodies (objects) emit and absorb infrared radiation
• As temperature of an object increases


  The quantity of infrared radiation emitted by the object increases
• 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 of an object 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