Physical World Units And Measurements Ques 3
3. 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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Answer:
Correct Answer: 3.(d)
Solution:
- (d) In steady state, the amount of heat flowing from one face to the other face in time $d t$ is given by
$H=\frac{kA(T_1-T_2) dt}{\ell}$
$\Rightarrow \frac{dH}{dt}=\frac{kA}{\ell} \Delta T \quad (k=$ coefficient of thermal conductivity)
$\therefore k=\frac{\ell dH}{Adt \Delta T}$
Unit of $k=Wm^{-1} K^{-1}$
BETA
