A60 w bulb has a cylindrical tungsten filament 4.3 cm in length with an emissivity of 0.47. assuming that conduction and convection losses and re-radiation from the surroundings are all negligible, find the diameter of the filament if it's operating temperature is 1750 °c. assume this temperature to be uniform at all points in the filament at any given time. use 5.67 x 10 w m² k4 for the stefan-boltzmann constant. a) 2.4 mm b) 0.995 mm c) 23.1 mm d) 1.778 mm e) 0.467 mm