For cooking the food,which of the following type of utensil is most suitable?

In the figure shown,$AB$ is a rod of length $30 \ cm$,area of cross-section $1 \ cm^2$ and thermal conductivity $336 \ SI$ units. The ends $A$ and $B$ are at constant temperatures $20^{\circ} C$ and $40^{\circ} C$ respectively. $A$ point $C$ of the rod is connected to ice at $0^{\circ} C$ in a thermally insulated box $D$ through a highly conducting wire of negligible heat capacity. The rate at which ice melts in the box is $\left(L_{ice}=80 \ cal \ g^{-1}\right)$.

Three rods each of length $l$ and cross-sectional area $A$ are joined in series between two heat reservoirs as shown in the figure. Their thermal conductivities are $2K$,$K$,and $\frac{K}{2}$,respectively. Assuming that the conductors are insulated from the surroundings,the temperatures $T_1$ and $T_2$ of the junctions in the steady-state condition are,respectively:

The area of the glass of a window of a room is $10\;m^2$ and thickness is $2\;mm$. The outer and inner temperatures are $40^{\circ}C$ and $20^{\circ}C$ respectively. The thermal conductivity of glass in the $MKS$ system is $0.2\;W/(m\cdot K)$. The heat flowing into the room per second will be:

$A$ 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 the same two reservoirs in time $t$?

Two plates of the same area are placed in contact. Their thicknesses as well as their thermal conductivities are in the ratio $2:3$. The outer surface of one plate is maintained at $10^{\circ} C$ and that of the other at $0^{\circ} C$. The temperature at the common surface is (in $^{\circ} C$)