28 Two coaxial cylinders of radius r and 3r are made of

Last updated: 6/5/2023

28 Two coaxial cylinders of radius r and 3r are made of material of thermal conductivity K and K respectively The equivalent thermal conductivity of substance for axial heat flow may be 1 3 O K 4 K K 9 K 8K2 9 r 3r 2 4 K K 6K 9 K K2 2