Four rods of same material and having the same cross section and length have been joined, as shown. The temperature of the junction of four rods will be ............... $^{\circ} C$

Two rods, one made of copper and the other steel of the same length and cross-sectional area are joined together. The thermal conductivity of copper is $385 \,Js ^{-1} m ^{-1} K ^{-1}$ and steel is $50 \,Js ^{-1} m ^{-1} K ^{-1}$. If the copper end is held at $100^{\circ} C$ and the steel end is held at $0^{\circ} C$, the junction temperature is ........... $C$ (Assuming no other heat losses)

Figure shows three different arrangements of materials $1, 2$ and $3$ to form a wall. Thermal conductivities are $k_1 > k_2 > k_3$ . The left side of the wall is $20\,^oC$ higher than the right side. Temperature difference $\Delta T$ across the material $1$ has following relation in three cases

A slab consists of two parallel layers of two different materials of same thickness having thermal conductivities $K_1$ and $K_2$ . The equivalent conductivity of the combination is

Which of the following factors affect the thermal conductivity of a rod?

Heat current is maximum in which of the following (rods are of identical dimension)