Consider a flat plate solar collector placed at the roof of a house. The temperatures at the inner and outer surfaces of glass cover are measured to be 28°C and 25°C, respectively. The glass cover has a surface area of 2.2 m ^{2} and a thickness of 0.6 cm and a thermal conductivity of 0.7 W / m \cdot C . Heat is lost from the outer surface of the cover by convection and radiation with a convection heat transfer coefficient of 10 W / m ^{2} \cdot{ }^{\circ} C and an ambient temperature of 15°C. Determine the fraction of heat lost from the glass cover by radiation.