Question
Explain the term thermal resistance. State its SI unit and dimensions.
✓
Answer
Consider expression for conduction rate,
$ P _{\text {cond }}= kA \frac{\left( T _1- T _2\right)}{ x }$
$\Rightarrow \frac{ T _1- T _2}{ P _{\text {cond }}}=\frac{ x }{ kA } \ldots \ldots$
2. Ratio $\frac{T_1-T_2}{P_{\text {cond }}}$ is called as thermal resistance $\left(R_T\right)$ of material.
The SI unit of thermal resistance is $^\circ C$ s/kcal or $^\circ C$ s/J and its dimensional formula is $[L^{-2}M^{-1}T^3K^1].$
$ P _{\text {cond }}= kA \frac{\left( T _1- T _2\right)}{ x }$
$\Rightarrow \frac{ T _1- T _2}{ P _{\text {cond }}}=\frac{ x }{ kA } \ldots \ldots$
2. Ratio $\frac{T_1-T_2}{P_{\text {cond }}}$ is called as thermal resistance $\left(R_T\right)$ of material.
The SI unit of thermal resistance is $^\circ C$ s/kcal or $^\circ C$ s/J and its dimensional formula is $[L^{-2}M^{-1}T^3K^1].$
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