The two ends of a rod of length $\mathrm{L}$ and a uniform cross-sectional area A are kept at two temperatures $T_1$ and $T_2\left(T_1>T_2\right)$. The rate of heat transfer, $\frac{\mathrm{dQ}}{\mathrm{dt}}$, through the rod in a steady state is given by :

• Correct answer
  A

  $\frac{\mathrm{dQ}}{\mathrm{dt}}=\frac{\mathrm{kA}\left(\mathrm{T}_1-\mathrm{T}_2\right)}{\mathrm{L}}$
• B

  $\frac{\mathrm{dQ}}{\mathrm{dt}}=\frac{\mathrm{kL}\left(\mathrm{T}_1-\mathrm{T}_2\right)}{\mathrm{A}}$
• C

  $\frac{\mathrm{dQ}}{\mathrm{dt}}=\frac{\mathrm{k}\left(\mathrm{T}_1-\mathrm{T}_2\right)}{\mathrm{LA}}$
• D

  $\frac{\mathrm{dQ}}{\mathrm{dt}}=\mathrm{kLA}\left(\mathrm{T}_1-\mathrm{T}_2\right)$

Hence, the correct answer is option: 'A'.