How would you identify a conduction heat transfer pattern on a thermogram?

• A. Uniform Temperature
• B. Isothermal Line
• C. Thermal Gradient
• D. None

Answer: (C)

Conduction moves heat through a solid from warmer to cooler areas, so a thermogram shows a gradual change in temperature along the material. This gradual change is a thermal gradient—the colors or shades shift smoothly in the direction of heat flow, indicating heat transfer through the substance. If the surface were uniform in temperature, there’d be no gradient to indicate conduction. An isothermal line marks a contour of equal temperature, not the ongoing change in temperature along the path of heat flow. Therefore, the sign of conduction is the presence of a thermal gradient.