Question

A hot wire radiates heat at 100 Watts. If its temperature measured in degrees Kelvin is doubled, then the power radiated will be what? 800Watts or 1600Watts

Answer 1

Power from a radiative body is a function of temperature to the fourth power.

Answer 2

Exactly. By the Stefan-Boltzman law,
\[ P_0 = A \epsilon \sigma T^4 \]

Hence if you double T,
\[ P = A \epsilon \sigma (2T)^4 = 2^4 (A \epsilon \sigma T^4) = 16 P_0 \]