Which scenario illustrates conduction as the primary mode of heat transfer?

Which scenario illustrates conduction as the primary mode of heat transfer?

• A. The Sun heating Earth by radiation
• B. Air currents heating a room
• C. Evaporation from a pot
• D. A metal spoon getting warm in hot soup

Answer: (D)

Conduction is heat transfer through direct contact, from a hotter region to a cooler region, without bulk motion of the material. In the hot soup scenario, heat moves from the soup into the metal spoon through the contact at the interface. The spoon’s molecules gain kinetic energy from the neighboring hot liquid and pass it along through the spoon, so the part in contact with the soup warms first and the heat propagates through the spoon. Metals are especially good at this because their particles transfer energy readily from one to the next. Other scenarios show different heat-transfer modes. The Sun heats Earth by radiation, using electromagnetic waves that don’t require contact. Heating a room by air currents involves convection, where moving fluid carries heat. Evaporation from a pot involves a phase change and latent heat, which is not conduction through direct contact.

Conduction is heat transfer through direct contact, from a hotter region to a cooler region, without bulk motion of the material. In the hot soup scenario, heat moves from the soup into the metal spoon through the contact at the interface. The spoon’s molecules gain kinetic energy from the neighboring hot liquid and pass it along through the spoon, so the part in contact with the soup warms first and the heat propagates through the spoon. Metals are especially good at this because their particles transfer energy readily from one to the next.

Other scenarios show different heat-transfer modes. The Sun heats Earth by radiation, using electromagnetic waves that don’t require contact. Heating a room by air currents involves convection, where moving fluid carries heat. Evaporation from a pot involves a phase change and latent heat, which is not conduction through direct contact.