If a black body at $400 \ K$ surrounded by atmosphere at $300 \ K$ has a rate of cooling '$R_0$',the same body at $900 \ K$,surrounded by the same atmosphere,will have a rate of cooling nearly:

$A$ certain substance emits only the wavelengths ${\lambda _1}, {\lambda _2}, {\lambda _3}$ and ${\lambda _4}$ when it is at a high temperature. When this substance is at a colder temperature,it will absorb only the following wavelengths:

If a vessel with black spots is heated to a very high temperature and then taken into a dark room,then:

Three objects colored black,gray,and white can withstand hostile conditions up to $2800\,^oC$. These objects are thrown into a furnace where each of them attains a temperature of $2000\,^oC$. Which object will glow brightest?

About black body radiation,which of the following is the wrong statement?

Three very large plates of the same area are kept parallel and close to each other. They are considered as ideal black surfaces and have very high thermal conductivity. The first and third plates are maintained at temperatures $2\ T$ and $3\ T$ respectively. The temperature of the middle (i.e.,second) plate under steady-state condition is