For an opaque body,the coefficient of transmission is:

$A$ spherical body of emissivity $e = 0.6$ placed inside a perfect black body is maintained at temperature $T$. The energy radiated per second by the body will be:

$A$ perfectly black body is placed in an enclosure (furnace) at room temperature. Then:

The following figure shows two air-filled bulbs connected by a $U$-tube partly filled with alcohol. One bulb is painted black and the other is painted white (or silver/shiny). What happens to the levels of alcohol in the limbs $X$ and $Y$ when an electric bulb placed midway between the two bulbs is lighted?

What are heat rays?

In which process is the rate of transfer of heat maximum?