1) conduction
the heat travels through the molecule of substance without movement of molecule themselves.(molecule doesn't travels.)
2) convection :
when the fluid (liquid and gas) heated the expands so the heated molecules become lighter and moves upward and cold molecules takes place . this process continues.
3) radiation :
in this way heat travels without any medium. it does not heat the medium approximately. heat travels in a straight line.
e g : heat from sun comes without any medium (zero atmosphere) to the earth by radiation.
2) convection :
3) radiation :
e g : heat from sun comes without any medium (zero atmosphere) to the earth by radiation.