"Good absorber of heat is good radiator of heat also" is

• The good absorbers of heat are good-emitters of heat.

Key Points

• Concept
  • The fact that 'good absorbers of heat are good emitters' is based on Kirchoff's radiation law.
  • The Kirchoff's radiation law states that at a given temperature the coefficient of absorption of a body is equal to its coefficient of emission.
• Explanation
  • A black body is an example of a good absorber of heat as well as a good emitter of heat.
  • The ease with which a black body can absorb a photon is the reverse process of emitting the one.
  • This entire cycle takes place because of the number of transitions that are associated with the EM field.

Additional Information

• Application of Kirchoff's Radiation Law,
  • Sand is rough black, so it is a good absorber and hence, in deserts, days will be very hot.
  • A person with black skin experiences more heat and cold as compared to white skin person.
  • When a green glass is heated in a furnace and taken out, it is found to glow with red light, because red and green are complementary colours.