Question

A uniform slab of dimension $10cm\times 10cm\times 1cm$ is kept between two heat reservoirs at temperatures${10}^{0}C$ and ${90}^{0}C$ . The larger surface areas touch the reservoirs . The thermal conductivity of the material is $0.80W/m{-}^{0}C$ . Find the amount of heat flowing through the slab per second.

Answer 1

Given : $K=0.80W/m^{o}C$ $\Delta T=90-10={80}^{o}C$

Length through which heat is flowing $l=1cm=0.01m$

Cross-sectional area $A=10\times 10c{m}^2={10}^{-2}{m}^2$

Heat flowing per second $Q=\frac{KA\Delta T}{l}$

$⟹Q=\frac{0.8\times {10}^{-2}\times 80}{0.01}=36J/s$