Which statement best explains conduction between two objects?

Which statement best explains conduction between two objects?

• A. They must be in contact and have the same temperature.
• B. They must be in contact and have different temperatures.
• C. They must be separated by air.
• D. They must be in vacuum

Answer: (C)

Heat transfer by conduction happens when two objects are in direct contact and heat flows because one is hotter than the other. The contact allows neighboring particles to collide and transfer kinetic energy, so energy moves from the hotter object toward the cooler one. If the objects are separated by air, conduction still occurs but is very weak since air is a poor conductor; most heat transfer in that situation would come from radiation or convection in the air. In a vacuum there is no medium to carry the energy, so conduction cannot occur. So the idea that conduction requires both contact and a temperature difference best captures how this mode of heat transfer works.

Heat transfer by conduction happens when two objects are in direct contact and heat flows because one is hotter than the other. The contact allows neighboring particles to collide and transfer kinetic energy, so energy moves from the hotter object toward the cooler one. If the objects are separated by air, conduction still occurs but is very weak since air is a poor conductor; most heat transfer in that situation would come from radiation or convection in the air. In a vacuum there is no medium to carry the energy, so conduction cannot occur. So the idea that conduction requires both contact and a temperature difference best captures how this mode of heat transfer works.