[填空题]
A 100-W lightbulb has/2+gep)ns;l j wfto.f a resisr-i0s mh4(;xqje sqh -tance of about $12\Omega$ 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 $\alpha\,=\,0.0060(C?)^{-1}$ . $^{\circ}\,C$
