Three rods $A, B,$ and $C$ of thermal conductivities $K, 2K$ and $4K$ and equal, cross-sectional areas and lengths $2l, l$ and $l$ respectively are connected as shown in the figure. If the ends of the rods are maintained at temperatures $100\ ^oC, 50\ ^oC,$ and $0\ ^oC$ respectively, then the temperature $\theta$ of the junction is
$\frac{300}{7}\ ^oC$
$\frac{300}{13}\ ^oC$
$\frac{200}{7}\ ^oC$
$\frac{200}{13}\ ^oC$
Two rods $A$ and $B$ of same cross-sectional are $A$ and length $l$ connected in series between a source $(T_1 = 100^o C)$ and a sink $(T_2 = 0^o C)$ as shown in figure. The rod is laterally insulated The ratio of the thermal resistance of the rod is
If the temperature of a black body increases from $7\,^oC$ to $287\,^oC$ then the rate of energy radiation increases by
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 $0.25$ ?
Hot water cools from $60\,^oC$ to $50\,^oC$ in the first $10\, min$ and to $42\,^oC$ in the next $10\, min$. The temperature of the surrounding is ........ $^oC$
Two rods having same area are used to connect two reservoirs at temperature $100\,^oC$ and $0\,^oC$ as shown. The temperature of junction is $70\,^oC$. If the rods are now interchanged, the temperature of junction will be ......... $^oC$