Question

A composite rod made of three rods of equal length
and cross-section as shown in the fig. The thermal
conductivities of the materials of the rods are K/2.
5K and K respectively. The end A and end B are at
constant temperatures. All heat entering the face
A goes out of the end B and there being no loss of
heat from the sides of the bar. The effective thermal
conductivity of the bar is
K/2
5K
(1) 15K/16
(3) 5K/16
(2) 6K/13
(4) 2K/13.​

Answer 1

correct option is option a