College of Massage Therapists of British Columbia (CMTBC) Practice Exam

What transfers heat by direct contact between two surfaces?

1. Convection

2. Conduction

3. Radiation

4. Evaporation

The correct answer is: Conduction

The transfer of heat by direct contact between two surfaces is known as conduction. This process occurs when two objects at different temperatures come into contact, allowing thermal energy to flow from the hotter object to the cooler one until thermal equilibrium is reached. In conduction, molecules in the hotter object vibrate more rapidly due to higher thermal energy and pass this energy to adjacent, slower-moving molecules in the colder object through collisions. Convection involves the movement of fluids (liquids or gases) and relies on the bulk movement of the fluid to transfer heat, making it distinct from conduction, which requires direct contact. Radiation transfers heat in the form of electromagnetic waves and does not require physical contact or a medium to transfer energy; an everyday example is the heat felt from the sun. Evaporation occurs when liquid molecules gain enough energy to change into vapor, but this process does not involve the transfer of heat in the manner of direct contact between surfaces. Conduction is crucial in various applications, including cooking and heating systems, making it a fundamental concept in the study of thermodynamics and heat transfer in physical sciences.