Thermal conductivity is the intrinsic property of a material which relates its ability to conduct heat. Heat transfer by conduction involves transfer of energy within a material without any motion of the material as a whole. Energy is transferred from the more energetic to the less energetic molecules. Thermal conductivity is defined as the quantity of heat transmitted through a unit thickness in a direction normal to a surface of unit area due to a unit temperature gradient under steady state conditions and when the heat transfer is dependent only on the temperature gradient. Equation of conductive heat flow is – $$H = kA \frac{(T_2 - T_1)}{x}$$ \(H\) is the steady state rate of heat transfer, \(k\) is the thermal conductivity of the sample, A is the cross sectional area and \((T2 – T1)\) is the temperature difference across the sample thickness ‘\(x\)’, assuming that the heat loss from the sides of the sample is negligible.