GATE 2025 MT – Question 59
The two sides of a 0.4 m thick copper plate are at 1000 and 500 °C. Assuming steady, one-dimensional conduction and ignoring end effects, the heat-flux magnitude is ______ $\times10^5\ \mathrm{W\,m^{-2}}$ (in integer). Given: copper thermal conductivity is 400 W m$^{-1}$ K$^{-1}$.
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Correct answer: 5 to 5
Explanation
Fourier’s law gives the magnitude $q=k\Delta T/L$. The temperature difference is 500 K.
Thus $q=400\times500/0.4=500000=5\times10^5\ \mathrm{W\,m^{-2}}$. The requested coefficient is **5**.