Two rods of crossectional area $A$ and $2A$ and equal length having thermal conductivities $2K$ and $3K$ are joined in parallel, then equivalent thermal conductivity of their combination will be-

The ratio of thermal conductivity of two rods of different materials is $5 : 4$. The two rods of same area and same thermal resistance will have lengths is the ratio

The temperature of furnace is $200\,^oC$, in its spectrum the maximum intensity is obtained at about $400\,\mathop A\limits^o $, If the maximum intensity is at $200\,\mathop A\limits^o $. Calculate the temperature of the furnace in ${}^oC$.  ……… $^oC$

Two rods $A$ and $B$ of different materials but same cross section are joined as in figure. The free end of $A$ is maintained at $100^o C$ and the free end of $B$ is maintained at $0^o C$. If $l_2 = 2l_1, K_1 = 2K_2$ and rods are thermally insulated from sides to prevent heat losses then the temperature $\theta$ of the junction of the two rods is …….. $^oC$

A cylindrical metallic rod in thermal contact with two reservoirs of heat at its two ends conducts an amount of heat $Q$ in time $t$. The metallic rod is melted and the material is formed into a rod of half the radius of the original rod. What is the amount of heat conducted by the new rod, when placed in thermal contact with same two reservoirs in time $t$