Two identical cubes, P and Q

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

Problem

Two identical cubes, P and Q, each of surface area 0.06 m20.06\,\text{m}^2, are placed in vacuum at the same distance from a lamp that delivers a uniform radiant flux of I=3.0×103 W m−2I=3.0\times10^{3}\,\text{W\,m}^{-2} perpendicular to one face of each cube. The remaining faces receive negligible radiation. Cube P has absorptive power 0.900.90 while cube Q has absorptive power 0.100.10. Assume: (i) ε=a\varepsilon = a for each cube, (ii) each cube loses energy only by radiation from all six faces, (iii) steady state is reached when power absorbed equals power emitted. Which of the following gives the steady-state temperature ratio TP/TQT_{P}/T_{Q}? (a) (9)1/4(9)^{1/4} (b) 33 (c) 11 (d) (1/9)1/4(1/9)^{1/4}

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