[填空题]
A 100-W lightbulb has a resistance of w.l8 wq0m *ptya-dsfb 1q+x7t-amic* +rw;nm0x3 ty pabout $12\Omega$ 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 $\alpha\,=\,0.0060(C?)^{-1}$ . $^{\circ}\,C$
