Physics

Problem

Two rectangular slabs each of area

A

are kept in series contact. The first slab is

2\,\text{cm}

thick with thermal conductivity

0.5\,\text{W m}^{-1}\text{K}^{-1}

and the second slab is

3\,\text{cm}

thick with thermal conductivity

0.1\,\text{W m}^{-1}\text{K}^{-1}

. The effective thermal conductivity of the composite slab is closest to a)

0.26\,\text{W m}^{-1}\text{K}^{-1}

0.30\,\text{W m}^{-1}\text{K}^{-1}

0.15\,\text{W m}^{-1}\text{K}^{-1}

0.17\,\text{W m}^{-1}\text{K}^{-1}