Question

Most of the energy needed for all the processes on earth comes directly or indirectly from the sun. There is no medium or material connecting the sun to the earth. Therefore, the only type of heat transfer possible to transfer energy from the sun to the earth is

A) condensation.
B) conduction.
C) convection.
D) radiation.

Answer 1

The answers is radiation because Conduction needs direct contact of atoms and convection needs a fluid. Therefore, radiation is the only type of heat transfer that needs no medium.