Question

Two rods of length d1 and d2 and coefficients of thermal conductivities k1 and k2 are kept touching each other. Both have the same area of cross-section. The equivalent thermal conductivity is

Answer 1

based on above information

the rods are placed in series so

R=R'+R"

so (d1+d2)/K=(d1/K1)+(d2/K2)

by solving the above equations we get

K=K1K2(d1+d2)/(K2d1+K1d2)

as area is equal we cancel area on both sides.

hope u understood