Physics - Heat & Thermo Question with Solution | TestHub

Radiation from a black body at the thermodynamic temperature ${\mathrm{T}}_1$ is measured by a small detector at distance ${\mathrm{d}}_1$ from it. When the temperature is increased to ${\mathrm{T}}_2$ and the distance to ${\mathrm{d}}_2$, the power received by the detector is unchanged. What is the ratio ${\mathrm{d}}_2/{\mathrm{d}}_1$?