Example 3.7: A 60 watt filament lamp loses all its energy by radiation from its surface. The emissivity of the surface is 0.5. The area of the surface is 5 x 105 m. Find the temperature of the filament ( o = 5.67 x 10-8J m 's"' K4).Example 3.8: Compare the rate of loss of heat from a metal sphere at 827 C with the rate of loss of heat from the same sphere at 427 .C, if the temperature of the surrounding is 27 C. SolutioExample 3.9: Assuming that the temperature at the surface of the Sun is 6000 K, find out the size of a virtual star (in terms of the size of Sun) whose surface temperature is 3000 K and the power radiated by the virtual star is 25 times the power radiated by the Sun. Treat both, the Sun and virtual star as a blackbody