The rate of dissipation of heat by a black body at temperature $T$ is $Q$. What will be  the rate of dissipation of heat by another body at temperature $2\,T$ and emissivity $0.25$ ?

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 ...... $\min$

Two ends of roads of length $L$ and radius $r$ of the same material are kept at the same temperature which of the following rod conducts most heat?

If the temperature of the sun were to increase from $T$ to $2T$ and its radius from $R$ to $2R$, then the ratio of the radiant energy received on earth to what it was previously, will be

Three rods of same dimensions have thermal conductivities $3K,\,2K$ and $K$. They are arranged as shown with their ends at $100\,^oC$, $50\,^oC$ and $0\,^oC$. Temperature of junction is

The rate of emission of radiation of a black body at $273^o C$ is $E$, then the rate of emission of radiation of this body at $0^o C$ will be