When heat is transferred by molecular collision, it is referred to as heat transfer by?
Liquids and gases are mainly heated by convection. In this process, there is a bodily movement of the heated molecules.
Convection heat transfer is the transfer of heat between two bodies by currents of moving gas or fluid. In free convection, air or water moves away from the heated body as the warm air or water rises and is replaced by a cooler parcel of air or water.