Physics – 2.3.4 Consequences of thermal energy transfer | e-Consult

When a hot object is placed in cooler surroundings, thermal energy is transferred via all three modes: conduction, convection, and radiation. Conduction occurs if the hot object is in direct contact with a cooler object; heat is transferred through molecular collisions. Convection happens if the hot object heats the air or liquid surrounding it, causing the heated fluid to rise and cooler fluid to sink, creating currents that distribute heat. Radiation occurs when the hot object emits infrared radiation, which travels through space and is absorbed by cooler objects.

The relative importance of each mode depends on the specific situation. For example, consider a blacksmith heating a piece of metal in a forge. Radiation from the forge is the initial source of heat, warming the metal. Conduction then plays a role as the blacksmith hammers the hot metal, transferring heat through the metal itself. However, convection is particularly important in this scenario. The hot air in the forge rises and circulates around the metal, ensuring that the entire piece is heated evenly. In this case, convection is significantly more important than conduction or radiation in maintaining the high temperature of the metal.