A 100-W light source consists of a filament that is in the form of a thin rectangular strip, 5 mm long by 2 mm wide, and radiates as a blackbody at 2900 K.
(a) Assuming that the glass bulb transmits all incident visible radiation, what is its efficiency? The efficiency is defined as the ratio of the visible radiant power to the consumed electrical power.
(b) Determine the efficiency as a function of filament temperature for the range from 1300 to 3300 K.