Two cylindrical conductors $A \text{and} B$ of same metallic material have their diameters in the ratio $1:2$ and lengths in the ratio $2:1$. If the temperature difference between their ends is same, the ratio of heat conducted respectively by $A \text{and} B$per second is

The temperature of bodies $X$ and $Y$ vary with time as shown in the figure. If emissivity of bodies $X$ and $Y$ are $e_x$ and $e_y$ and absorptive powers are $A_x$ and $A_y$, (assume other conditions are identical for both), then

Three graphs marked as $1$, $2$, $3$ representing the variation of maximum emissive power and wavelength of radiation of the sun, a welding arc and a tungsten filament. Which of the following combination is correct

Two rectangular blocks, having identical dimensions, can be arranged either in the configuration $\mathrm{I}$ or in the configuration $\mathrm{II}$ as shown in the figure. One of the blocks has thermal conductivity $k$ and the other $2k$. The temperature difference between the ends along the $x$-axis is the same in both configurations. It takes $9 \mathrm{s}$ to transport a certain amount of heat from the hot end to the cold end in the configuration $\mathrm{I}$. The time to transport the same amount of heat in the configuration $\mathrm{II}$ is: