A tungsten filament lamp operates at 2000 K

PHYSICS · Single correct · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter

Problem

A tungsten filament lamp operates at 2000 K. Its surface emissivity is 0.25 and the area of the filament is 1.0×10−4 m21.0\times10^{-4}\,\text{m}^2. Because of surface changes, the emissivity falls to 0.20. If the same 60 W of radiant power is to be maintained from the same area, to what temperature must the filament be heated? (a) 1900 K1900\,\text{K} (b) 2110 K2110\,\text{K} (c) 2240 K2240\,\text{K} (d) 2500 K2500\,\text{K}

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