Which of the following material is most suitable for cooking utensils?

Three rods of equal length and cross-sectional area with thermal conductivities $K, 2K$,and $3K$ are joined as shown in the figure. The temperatures of their outer ends are $110\ ^oC, 20\ ^oC$,and $0\ ^oC$ respectively. Find the temperature of the junction in $^oC$.

Wires $A$ and $B$ have identical lengths and have circular cross-sections. The radius of $A$ is twice the radius of $B$,$i.e.$,${r_A} = 2{r_B}$. For a given temperature difference between the two ends,both wires conduct heat at the same rate. The relation between the thermal conductivities is given by:

The area of a glass window is $10 \ m^2$ and its thickness is $2 \ mm$. The outside and inside temperatures are $40^{\circ}C$ and $20^{\circ}C$ respectively. The thermal conductivity in $MKS$ units is $0.2$. The heat conducted per second into the room is ......

Why do some cooking vessels have a copper coating at the bottom?

According to the experiment of Ingen Hausz, the relation between the thermal conductivity $K$ of a metal rod and the length $l$ of the rod up to which the wax melts is: