[填空题]
A 100-W lightbulb has a resism2xws( :shk8g tance of a1an:(z z;aucfxv()mabout $12\Omega$ when cold ($20^{\circ}\,C$) and $140\Omega$ when on (hot). Estimate the temperature of the filament when hot assuming an average temperature coefficient of resistivity $\alpha\,=\,0.0060(C?)^{-1}$ . $^{\circ}\,C$
