An energy-efficient double-paned window consists of two panes of glass, the with thickness...

An energy-efficient double-paned window consists of two panes of glass, the with thickness L\ and thermal conducti vi ty k 1, separated by a layer of air of thickness L 2 and thermal conductivity k 2. Show that the equilibrium rate of heat flow through this window per unit area, A, is

In this expression, T 1 and T 2 are the temperatures on either side of the window.