The ends of a metal bar of constant cross-sectional area are maintained at temperatures $T_1$ and $T_2$ which are both higher than the temperature of the surroundings. If the bar is unlagged,which one of the following sketches best represents the variation of temperature with distance along the bar?

Which of the following statements is/are $CORRECT$?
$(i)$ $A$ body with large reflectivity is a poor emitter.
$(ii)$ $A$ brass tumbler feels much colder than a wooden tray on a chilly day.
$(iii)$ The Earth without its atmosphere would be inhospitably cold.
$(iv)$ Heating systems based on the circulation of steam are more efficient in warming a building than those based on the circulation of hot water.

$A$ black body radiates maximum energy at wavelength $\lambda$ and its emissive power is $E$. Now, due to a change in the temperature of that body, it radiates maximum energy at wavelength $\frac{2 \lambda}{3}$. At that temperature, the emissive power is:

$A$ black body radiates maximum energy at wavelength $\lambda$ at temperature $T_1$ and its emissive power is $E$. When the temperature of the body is changed to $T_2$, it radiates maximum energy at wavelength $\frac{2\lambda}{3}$, then the emissive power will become

The dimensions of $\sigma b^4$, where $\sigma$ is Stefan's constant and $b$ is Wien's constant, are:

In a closed room,heat transfer takes place by