In a manufecturing process, a transparent film is bonded to a substrate as shown in given figure. To cure the  bond at a temperature T0, a radiant heat source is used to provide a heat flux q0(W/m2), all of which is absorbed at a the bonded surface. The back of the subsubstrate is maintained at a temperature T1 while the free surface of the film is exposed to air at a temperature T∞ and a convective heat transfer coefficient h.

(a) Assuming the following conditions T∞ = 20 °C, h = 50 W/(m2K) and T1 = 30 °C,  calculate the heat flux q0 that is required to maintain the bonded surface at T0 = 60° C.

(b) If the film is not transparent and all of the radiant heat flux is absorbed at its upper surface, determine the heat flux required to acheive bonding.