Explain how Fourier's law of conduction (in one-dimensional cartesian system) can be applied to experimentally measure the thermal conductivity of solid materials. What are the necessary conditions and assumptions? [20 marks] Two surfaces make up an enclosure where surface 1 is flat and has area A1, temperature T1 and emissivity 1. Surface 2 is black and has temperature T2. Show that the net power transfer rate (net heat flux) in W/m2 at surface 1 is given by 1(T14T24)