A square aluminium plate of side is maintained at in a room where the walls are at

PHYSICS · Multi-part · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics

Problem

A square aluminium plate of side

0.20\,\text{m}

is maintained at

500\,\text{K}

in a room where the walls are at

300\,\text{K}

. The surface of the plate has emissivity

\varepsilon = 0.30

. Take

\sigma = 5.67\times10^{-8}\,\text{W\,m}^{-2}\,\text{K}^{-4}

. (i) Calculate the net power radiated by one face of the plate. (ii) How much energy does the plate lose through that face in

10\,\text{min}

? (iii) If the plate were an ideal absorber at

500\,\text{K}

in the same room, by what factor would the net power radiated change? Show your working.