Three rods of same dimensions are arranged as shown in the figure. They have thermal conductivities K1, K2 and K3. The points A and B are maintained at different temperatures. For the heat to flow at the same rate along ACB and AB,
1
\(K_3=\frac{K_1 K_2}{K_1+K_2}\)
2
K3 = 2(K1 + K2)
3
\(K_3=\frac{1}{2}\left(K_1+K_2\right)\)
4
K3 = K1 + K2