Q. The tungsten filament of an electric lamp has a surface area $A$ and a power rating $P$. If the emissivity of the filament is $\varepsilon$ and $\sigma$ is Stefan’s constant, the steady temperature of the filament will be
A) $T = \left( \frac{P}{A\varepsilon\sigma} \right)^{4}$
B) $T = \left( \frac{P}{A\varepsilon\sigma} \right)$
C) $T = \left( \frac{A\varepsilon\sigma}{P} \right)^{\frac{1}{4}}$
D) $T = \left( \frac{P}{A\varepsilon\sigma} \right)^{\frac{1}{4}}$
Explanation
(d) $\frac{Q}{t} = P = A\varepsilon\sigma T^{4}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.