Heat transfer through direct contact between materials is called:

• A. Convection
• B. Conduction
• C. Radiation
• D. Absorption

Answer: (B)

Direct contact heat transfer is conduction. When two materials touch, energy moves from the hotter to the cooler object through particle interactions at the interface. In solids, this happens as lattice vibrations and, in metals, free electrons carry energy from the heated region toward cooler regions, so the temperature difference even out over time. The rate of conduction depends on how well the materials conduct heat and the size of the temperature difference. A familiar example is a metal spoon in hot soup: heat travels along the spoon from the hot end to the cooler end and can eventually be felt in your hand.

Convection, by contrast, requires fluid movement to transport heat, such as air currents or boiling water. Radiation transfers heat via electromagnetic waves and can occur through a vacuum, without touching. Absorption is about taking in energy, not the mechanism of heat transfer itself.