Question

Heat flows through a wooden board 30mm thick at 0.0086 W/cm² when one of it's sides is 20°C warmer than the other. Determine the thermal conductivity of the wood.​

Answer 1

Since,

$$Q=\frac{kA}{L}\Delta T\implies k=\frac{Q}{A}\frac{L}{\Delta T}$$

In this case, $\Delta T=20K,\frac{Q}{A}=0.0086W/cm^2=86W/m^2$ ,$L=30mm=0.03m$

Thus, on applying the above formula we get,

$$k=86\cdot(0.03/20)=0.129WmK^{-1}$$