____________ nanotubes are used as strengthening rods and toughening elements in structural composite materials.

Q. Two rods $A$ and $B$ of different materials are welded together as shown in figure. Their thermal conductivities are $K_1$ and $K_2$. The thermal conductivity of the composite rod will be :

Q. Two rods A and B of different materials are welded together as shown in figure. Their thermal conductivities are $K_1$ and $K_2$. The thermal conductivity of the composite rod will be

Q.

Two rods A and B of different materials are welded together as shown in Figure. If their thermal conductivities are $k_1$and $k_2$, the thermal conductivity of the composite rod will be

Q.

Two rods A and B of different materials are welded together as shown in the figure. If their thermal conductivities are $k_1$ and $k_2$, the thermal conductivity of the composite rod will be

Q. A composite bar of length $L=L_1+L_2$ is made up from a rod of material $1$ and of length $L_1$ attached to a rod of material $2$ and of length $L_2$ as shown. If ${\alpha }_1$ and ${\alpha }_2$ are their respective coefficients of linear expansion then equivalent coefficient of linear expansion for the composite rod is: