Which demonstrates conduction?

Which demonstrates conduction?

• A. A marshmallow held over a fire
• B. Ice cream melting in the sun
• C. A bulb releasing light energy
• D. Cool feet walking across a hot pavement

Answer: (D)

Conduction is heat transfer through direct contact, where energy moves from the hotter object to the cooler one by particle interactions. Walking barefoot on hot pavement demonstrates this: the pavement is hotter than your feet, and as they touch, heat flows from the pavement into your feet, warming them through direct contact. The other scenarios involve different ways heat can move or energy can be emitted: ice cream melting in the sun is heating by radiation from sunlight; a lamp emitting light energy is about light emission (with any heat being incidental); a marshmallow over a fire is heated mainly by radiation from the flames, with conduction only if the marshmallow is touching a heated surface. Therefore, the direct contact heat transfer shown when cool feet meet hot pavement is the clearest example of conduction.

Conduction is heat transfer through direct contact, where energy moves from the hotter object to the cooler one by particle interactions. Walking barefoot on hot pavement demonstrates this: the pavement is hotter than your feet, and as they touch, heat flows from the pavement into your feet, warming them through direct contact. The other scenarios involve different ways heat can move or energy can be emitted: ice cream melting in the sun is heating by radiation from sunlight; a lamp emitting light energy is about light emission (with any heat being incidental); a marshmallow over a fire is heated mainly by radiation from the flames, with conduction only if the marshmallow is touching a heated surface. Therefore, the direct contact heat transfer shown when cool feet meet hot pavement is the clearest example of conduction.