The left end of a copper rod (length = 20 cm , area of cross section = 0.20 cm^2 ) is kept at 20^ ^ ^ C while the right end is kept at 80^ ^ ^ C . Ignoring any heat loss due to radiation, determine the heat current

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Correct answer: B. 2.31 J s^ -1

Given parameters of the copper rod:

Length,

L = 20 \text{ cm} = 0.20 \text{ m}

Area of cross section,

A = 0.20 \text{ cm}^2 = 0.20 \times 10^{-4} \text{ m}^2

Temperature difference,

\Delta T = 80^{}^{{}^{\circ}} \text{C} - 20^{}^{{}^{\circ}} \text{C} = 60^{}^{{}^{\circ}} \text{C}

Thermal conductivity,

k = 385 \text{ W m}^{-1} ^{}^{{}^{\circ}} \textC^{-1}

The heat current

H

through the rod is given by Fourier's law of heat conduction:

H = \dfrac{k A \Delta T}{L}

Substituting the given values:

H = \dfrac{385 \times 0.20 \times 10^{-4} \times 60}{0.20}

H = 385 \times 10^{-4} \times 60

H = 23100 \times 10^{-4}

H = 2.31 \text{ J s}^{-1}

The left end of a copper rod (length = 20 cm , area of cross...

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