Two flat sheets of thickness `d_1 and d_2` and thermal conductivities `K_1 and K_2` are joined together. If the open face of the first sheet is maintained at temperature `theta_1` and the other open face of the second sheet at `theta_2`. Calculate the temperature of the interface of two sheets. What is the conductivity of the composite sheets ?

Answer

`theta= (K_1 theta_1 // d_1 + K_2 theta_2 // d_2 )/( K_1 // d_1 + K_2 // d_2) , (2 K_1 K_2)/( K_1 + K_2) `