Question

Two identical rods with different thermal conductivities K₁ and K₂ and different temperatures are first placed along length and then along area, then the ratio of rates of heat flow in both cases is –

• A. $\frac{4K_{1}K_{2}}{(K_{1} + K_{2})^{2}}$
• B. $\frac{K_{1}}{K_{2}}$
• C. $\frac{K_{1} + K_{2}}{K_{1}–K_{2}}$
• D. None of these

Answer 1

Answer: (A)

$\frac{4K_{1}K_{2}}{(K_{1} + K_{2})^{2}}$

Answer 2

K_S = $\frac{2K_{1}K_{2}}{K_{1} + K_{2}}$, K_P = $\frac{K_{1} + K_{2}}{2}$

$\frac{H_{S}}{H_{P}}$ = $\frac{K_{S}}{K_{P}}$ = $\frac{4K_{1}K_{2}}{(K_{1} + K_{2})^{2}}$