Physical World Units and Measurements - Result Question 1
1. The unit of thermal conductivity is : [2019]
(a) $J m K^{-1}$
(c) $W m K^{-1}$
(b) $J m^{-1} K^{-1}$
(d) $W m^{-1} K^{-1}$
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Solution:
- (d) In steady state, the amount of heat flowing from one face to the other face in time $d t$ is given by
$H=\frac{kA(T_1-T_2) dt}{\ell}$
$\Rightarrow \frac{dH}{dt}=\frac{kA}{\ell} \Delta T(k=$ coefficient of thermal conductivity)
$\therefore k=\frac{\ell dH}{Adt \Delta T}$
Unit of $k=Wm^{-1} K^{-1}$
