AIIMS 2019 Physics Heat Transfer MCQ Question

The rate of heat transfer $\frac{dQ}{dt}$ through a rod in a steady state is described by Fourier's law of heat conduction, which states that $\frac{dQ}{dt} = \frac{kA(T_1 - T_2)}{L}$, where $k$ is the thermal conductivity, $A$ is the cross-sectional area, $T_1$ and $T_2$ are the temperatures at the ends of the rod, and $L$ is the length of the rod. This formula indicates that heat transfer is directly proportional to the temperature difference and the area, and inversely proportional to the length of the rod, making option C correct.

Options A and B are incorrect because they either misplace the factors or do not correctly represent the relationship as dictated by Fourier's law. Option D incorrectly suggests that heat transfer is inversely proportional to the area, which contradicts the principles of thermal conduction.