Physics - Heat & Thermo Question with Solution | TestHub

The emissivity and surface area of the tungsten filament of an electric bulb are 0.35 and $0.25\times 10^{-4}$ $m^2$ respectively. The operating temperature of the filament is 3000 K. If $\sigma =5.67\times 10^{-8}$ W $m^{-2}$$K^{-4}$, then the power of the bulb is approximately: