Heat transfer by direct contact with a solid object is known as conduction. Which choice best illustrates conduction?

Heat transfer by direct contact with a solid object is known as conduction. Which choice best illustrates conduction?

• A. Direct skin-to-skin touch
• B. Heat transfer through air
• C. Heat transfer through water
• D. Heat transfer from radiation

Answer: (A)

Conduction is heat transfer through direct contact between substances, with energy moving from the hotter to the cooler surface via molecular interactions at the contact point. Direct skin-to-skin touch shows this clearly: two solid bodies in intimate contact allow energy to flow from the warmer skin to the cooler skin through the solid surfaces until temperatures even out. Heat transfer through air is mainly convection (movement of the gas carrying energy) with some conduction, but the presence of a gap means there isn’t direct solid contact. Heat transfer through water can occur by conduction in the fluid, but it involves a medium other than direct solid contact. Heat transfer by radiation happens without contact, through electromagnetic waves.

Conduction is heat transfer through direct contact between substances, with energy moving from the hotter to the cooler surface via molecular interactions at the contact point. Direct skin-to-skin touch shows this clearly: two solid bodies in intimate contact allow energy to flow from the warmer skin to the cooler skin through the solid surfaces until temperatures even out.

Heat transfer through air is mainly convection (movement of the gas carrying energy) with some conduction, but the presence of a gap means there isn’t direct solid contact. Heat transfer through water can occur by conduction in the fluid, but it involves a medium other than direct solid contact. Heat transfer by radiation happens without contact, through electromagnetic waves.