Searle’s Thermal Conductivity Apparatus is a laboratory instrument used to measure the thermal conductivity of materials. It consists of a metal rod, typically made of copper or brass, with two heating coils at each end and a thermometer inserted in the middle. The sample material to be tested is placed in between the two heating coils, and the temperature gradient along the rod is measured as heat flows through the sample.

By measuring the temperature gradient and applying Fourier’s Law of Heat Conduction, the thermal conductivity of the material can be calculated. Searle’s Thermal Conductivity Apparatus is widely used in materials science, engineering, and physics research to study the thermal properties of materials and to develop new materials with improved thermal conductivities. It is named after Henry Searle, a British physicist who invented the apparatus in the late 19th century.