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Question: The coefficients of thermal conductivity of copper, mercury and glass are respectively K<sub>c</sub>...

The coefficients of thermal conductivity of copper, mercury and glass are respectively Kc, Km and Kg such that Kc> Km> Kg. If the same quantity of heat is to flow per second per unit area of each and corresponding temperature gradients are respectively Xc, Xm and Xg then

A

Xc= Xm = Xg

B

Xc>Xm>Xg

C

Xc<Xm<Xg

D

Xm<Xc<Xg

Answer

Xc<Xm<Xg

Explanation

Solution

dQ/dtA=K(ΔθΔx)\frac{dQ/dt}{A} = K\left( \frac{\Delta\theta}{\Delta x} \right) ⇒ Rate of flow of heat per unit area = Thermal conductivity × Temperature gradient

Temperature gradient (X) 1Thermal conductivity(K)\propto \frac{1}{\text{Thermal conductivity}(K)}

As KC > Km > Kg therefore XC<Xm<XgX_{C} < X_{m} < X_{g}.