Conduction is the direct transfer of energy between two objects in physical contact with each other. What is necessary to initiate this transfer?

• A. A Temperature Difference
• B. Equal Temperatures
• C. No Temperature Difference
• D. Pressure Difference

Answer: (A)

Conduction starts because there is a driving force: a difference in temperature. When two objects touch, the particles in the hotter object have more kinetic energy and collide with the cooler object, transferring energy to it. In solids, this transfer happens through lattice vibrations and, in metals, also through free electrons that move energy quickly from the hot side to the cold side. The process continues until both objects reach the same temperature, at which point there’s no net energy flow. If temperatures are equal from the start, there’s no driving force for conduction. A pressure difference isn’t what initiates conduction; it might affect contact quality, but it doesn’t provide the energy that moves heat.