Two cylindrical rods of lengths `l_(1)` and `l_(2)`, radii `r_(1)` and `r_(2)` have thermal conductivities `k_(1)` and `k_(2)` respectively. The ends of the rods are maintained at the same temperature difference. If `l_(1) =2l_(2)` and `r_(1) =r_(2)//2`, the rates of heat flow in them will be the same if `k_(1)//k_(2)` is:

Consider two rods of equal cross - sectionai area A, one of Aluminium and other of iron joined end to end as shown in figure -4.8. Length of the two rods and their thermal coductivities are l_(1) , k_(1) and l_(2),k_(2) respectively . If the ends of the rods are maintained at temperature T_(1) and T_(2),(T_(1)gt T_(2)) find the temperature of the junction in steady state .

Two rods of length l_(1) and l_(2) and coefficients of thermal conductivities k_(1) and K_(2) are kept touching each other. Both have the same area of cross-section. The equivalent of thermal conductivity is

In above diagram, a combined rod is formed by connecting two rods of length l_(1) and l_(2) respectively and thermal conductivity k_(1) and k_(2) respectively. Temperature of ends of rods are T_(1) and T_(2) constant, then find the temperature of their contact surface ?

Two plates each of area A thickness L_(1) and L_(2) thermal conductivities K_(1) and K_(2) respectively are joined to from a single plate of thickness (L_(1)+L_(2)) If the temperatures of the free surfaces are theta_(1) and theta_(2) Calculate (a) Rate of flow of heat (b) Temperature of interface .

Two rods one is semi circular of thermal conductivity K_(1) and otheir is straight of thermal conductivity K_(2) and of same cross sectional area are joined as shown in the The points A and B are maintained at same temperature difference. If rate of flow of heat is same in two rods then K_(1)//K_(2) is .

Two rods of the same length and diameter, having thermal conductivities K_(1) and K_(2) , are joined in parallel. The equivalent thermal conductivity to the combinationk is