The thermal conductivity of brick is `1.7 W m^(-1) K^(-1)`, and that of cement is `2.9 W m^(-1) K^(-1)`.What thickness of cement will have same insulation as the brick of thickness `20 cm`.

The figure shows the cross-section of the outer wall of a house buit in a hill-resort to keep the house insulated from the freezing temperature of outside. The wall consists of teak wood of thickness L_(1) and brick of thickness (L_(2) = 5L_(1)) , sandwitching two layers of an unknown material with identical thermal conductivites and thickness. The thermal conductivity of teak wood is K_(1) and that of brick is (K_(2) = 5K) . Heat conducion through the wall has reached a steady state with the temperature of three surfaces being known. (T_(1) = 25^(@)C, T_(2) = 20^(@)C and T_(5) = - 20^(@)C) . Find the interface temperature T_(4) and T_(3) .

The figure shows the cross-section of the outer wall of a house buit in a hill-resort to keep the house insulated from the freezing temperature of outside. The wall consists of teak wood of thickness L_(1) and brick of thickness (L_(2) = 5L_(1)) , sandwitching two layers of an unknown material with identical thermal conductivites and thickness. The thermal conductivity of teak wood is K_(1) and that of brick is (K_(2) = 5K) . Heat conducion through the wall has reached a steady state with the temperature of three surfaces being known. (T_(1) = 25^(@)C, T_(2) = 20^(@)C and T_(5) = - 20^(@)C) . Find the interface temperature T_(4) and T_(3) .

A cylindrical steel rod of length 0.10 m and thermal conductivity 50 W.m^(-1) K^(-1) is welded end to end to copper rod of thermal conductivity 400 W.m^(-1). K^(-1) and of the same area of cross section but 0.20 m long. The free end of the steel rod is maintained at 100^(@)C and that of the copper and at 0^(@)C . Assuming that the rods are perfectly insulated from the surrounding, the temperature at the junction of the two rods–

If the thermal conductivity of the material of a conductor is 375 W m^(-1)K^(-1) , then calculate the thermal resistance of a 20 mm thick and 1.5 m length of the rod. If an identically shaped rod but of thermal conductivity 600 Wm^(-1)K^(-1) is connected in (1) series and (2) parallel, then calculate the effective conductivities of the combinations.

The thickness of a brick wall is 0.25m. The temperatures inside and outside or 24^(@) C and 42^(@) C. Given Thermal conductivity of brick = 0.15 Wm^(-1)K^(-1) , then calculate the total amount of heat conducted in a time interval of 30 minutes due to a 25 m^2 wall.

Figure shows the cross section of a wall made of white pine of thickness L_(a) and brick of thickness L_(d) = = 2.0 L_(a) , sandwiching two layers of unknonw material with identical thicknesses and thermal conductivities. The thermal conductivity of the pine is k_(a) and that of the brick is k_(d) ( = 5.0k_(a)) . The face area A of the wall is unknown. Thermal conduction through the wall has reached the steady state, the only known interface temperatures are T_(1) = 25^(@)C, T_(2) = 20^(@)C , and T_(5 ) = - 10^(@)C . What is interface temperature T_(4) ?

Show that the SI units of thermal conductivity are W//m-K .

Show that the SI units of thermal conductivity are W//m-K .