A cylindrical metal rod with emissivity has radius and length

PHYSICS · Multi-part · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter

Problem

A cylindrical metal rod with emissivity

0.60

has radius

2.0\,\text{cm}

and length

20\,\text{cm}

. Its flat ends are closed. The rod is initially at a uniform temperature of

700\,\text{K}

and is placed in a very large, perfectly black surrounding kept at

0\,\text{K}

(so that re-absorption from surroundings may be neglected). Take

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

. (i) Compute the total surface area of the rod that is effective in emitting radiation. (ii) Calculate the amount of thermal energy it radiates in

5\,\text{min}