Answer:
c. 98 W
Explanation:
[tex]P_{i}[/tex] = initial power delivered by bulb at initial temperature = 40 W
[tex]T_{i}[/tex] = initial temperature of filament = 2000 K
Now the temperature of filament of the bulb rises
[tex]P_{f}[/tex] =Final power delivered by bulb at higher temperature
[tex]T_{f}[/tex] = Final higher temperature of filament = 2500 K
As per Stefan's law, the power delivered by the bulb depends directly on fourth power of the temperature. hence we can write
[tex]\frac{P_{f}}{P_{i}} = \frac{T_{f}^{4} }{T_{i}^{4}} \\\frac{P_{f}}{40} = \frac{2500^{4} }{2000^{4}}\\\\P_{f} = (2.44) (40)\\P_{f} = 98 W[/tex]
