Two plates of same thickness, of coefficient of thermal conductivities K1 and K2 and areas of cross-section A1 and A2 are connected as shown in figure. The common coefficient of thermal conductivity K will be:
1
K1A1 + K2A2
2
\(\frac{{{K_1}{A_1} + {K_2}{A_2}}}{{{A_1} + {A_2}}}\)
3
\(\frac{{{K_1}{A_2} + {K_2}{A_1}}}{{{A_1} + {A_2}}}\)
4
\(\frac{{{K_1}{A_1}}}{{{K_2}{A_2}}}\)