alleryStart learning →Fourier's law of heat conduction (1D) states:
A$q = kAT$
B$q = -kA\frac{dT}{dx}$ — heat flow rate is proportional to negative of temperature gradient times area
C$q = h(T_s - T_\infty)$
D$q = \sigma T^4$
Answer & Solution
Correct answer: B. $q = -kA\frac{dT}{dx}$ — heat flow rate is proportional to negative of temperature gradient times area
**Fourier's law:** q = −kA·dT/dx.
The negative sign means heat flows from hot to cold (down the gradient).
k is thermal conductivity (W/m·K).
Heat flux (per area) = q'' = q/A = −k·dT/dx (W/m²).
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