Consider one-dimensional steady state heat conduction along x-axis $$\left( {0 \le x \le L} \right),$$ through a planewall with the boundary surfaces $$(x=0$$ and $$x=L)$$ maintained at temperatures of $${0^ \circ }C$$ and $${100^ \circ }C$$. Heat is generated uniformly throughout the wall. Choose the CORRECT statement.

A pipe of $$25$$ $$mm$$ outer diameter carries steam. The heat transfer coefficient between the cylinder and surrounding is $$5$$ $$W/{m^2}K.$$ It is propsed to reduce the heat loss from the pipe by adding insulation having a thermal conductivity of $$0.05$$ $$W/mK$$. Which one of the following statements is TRUE?

In a composite slab, the temperature at the interface (T_inter) between two materials is equal to the average of the temperatures at the two ends. Assuming steady one-dimensional heat conduction, which of the following statements is true about the respective thermal conductivities?

In case of one dimensional heat conduction in a medium with constant properties, $$T$$ is the temperature at position $$x,$$ at time $$t.$$ Then $${{\partial T} \over {\partial t}}$$ is proportional to