The filament of an incandescent lightbulb is made of tungsten. At room temperature of 20.0°C the filament has a resistance of 10.0 Ω.
(a) What is the power dissipated in the lightbulb immediately after it is connected to a 120 V emf (when the filament is still at 20.0°C)? 

(b) After a brief time, the lightbulb filament has changed temperature and it glows brightly. The current is now 0.833 A. What is the resistance of the lightbulb now? 

(c) What is the power dissipated in the lightbulb when it is glowing brightly as in part (b)? 

(d) What is the temperature of the filament when it is glowing brightly? 

(e) Explain why incandescent lightbulbs usually burn out when they are first turned on rather than after they have been glowing for a long time.