The adjoining diagram shows the spectral energy density distribution $E_\lambda $ of a black body at two different temperatures. If the areas under the curves are in the ratio $16 : 1$, the value of temperature $T$ is  ......... $K$

Six wires each of cross-sectional area $A$ and length $l$ are combined as shown in the figure. The thermal conductivities of copper and iron are $K_1$ and $K_2$ respectively. The equivalent thermal resistance between points $A$ and $C$ is

A body cools from $62\,^oC$ to $50\,^oC$ in $10\, minutes$ and to $42\,^oC$ in the next $10\, minutes$. The temperature of the surrounding is ........ $^oC$

A body cools from a temperature $60\,^oC$ to $40\,^oC$ in $10$ minutes. The room temperature is $20\,^oC$ . Assume that Newton's law of cooling is applicable. The temperature of the body at the end of next $10$ minutes will be......... $^oC$

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-

Two identical square rods of metal are welded end to end as shown in figure $(a),\, 20$ $calories$ of heat flows through it in $4\,minutes$ . If the rods are welded as shown in figure $(b)$ , the same amount of heat will flow through the rods in ...... $\min$