Three rods of same dimensions are arranged as shown in the figure. They have thermal conductivities `K_1` , `K_2` and `K_3` . The points `A` and `B` are mainted at different temperatures. For the heat to flow at the same rate along `ACB` and `AB` ,
`K_3` = `(K_1K_2)/(K_1+K_2)`
`K_3` = 2(`K_1 + K_2)`
`K_3 = 1/2 (K_1 + K_2)`
`K_3= K_1+K_2`