2) A copper plat has dimensions 1m × 2m × 0.08m. The one of the largest surfaces is kept at 100 °C and other one is at 0 °C. Thermal conductivity of the copper plate k is 400 W/mK. What is the rate at which energy flows through the plate and the thermal resistance of the plate? (Marks: 02)  Published on 19 Oct 15
a. 800 kW, 1 × 10^{– 3} K/W
b. 800 kW, 1 × 10^{– 4} K/W
c. 80000 W, 1 × 10^{– 3} K/W
d. 80000 W, 1 × 10^{– 4} K/W
Answer
Explanation

ANSWER: 800 kW, 1 × 10^{– 4} K/W
Explanation: According to the Fourier's law of heat conduction, Rate of heat flow is given by,
qk = ( k A ΔT ) / l
= (400 × 1 × 2 × (80 – 0)) / 0.08 =800 kW
And thermal resistance is given by,
R_{t} = l / kA
= 0.08 / (400 × 1 × 2) =1 × 10^{– 4} K/W

