A deep rectangular pond of surface area $A,$ containing water (denstity $=\rho,$ specific heat capactly $=s$ ), is located In a region where the outside air temperature is at a steady value of $-26^{\circ} {C}$. The thickness of the frozen ice layer In this pond, at a certaln Instant Is $x$.
Taking the thermal conductivity of Ice as ${K}$, and its specific latent heat of fusion as $L$, the rate of Increase of the thickness of ice layer, at this instant would be given by
$26 \mathrm{K} / \mathrm{\rho r}(\mathrm{L}-4 \mathrm{s})$
$26 \mathrm{K} /\left(\rho \mathrm{x}^{2}-\mathrm{L}\right)$
$26 K /(\rho x L)$
$26 \mathrm{K} / \mathrm{\rho r}(\mathrm{L}+4 \mathrm{s})$
$A$ cylinder of radius $R$ made of a material of thermal conductivity ${K_1}$ is surrounded by a cylindrical shell of inner radius $R$ and outer radius $2R$ made of material of thermal conductivity ${K_2}$. The two ends of the combined system are maintained at two different temperatures. There is no loss of heat across the cylindrical surface and the system is in steady state. The effective thermal conductivity of the system is
When two ends of a rod wrapped with cotton are maintained at different temperatures and after some time every point of the rod attains a constant temperature, then
For the figure shown, when arc $ACD$ and $ADB$ are made of same material, the heat carried between $A$ and $B$ is $H$ . If $ADB$ is replaced with another material, the heat carried becomes $2H$ . If the temperatures at $A$ and $B$ are fixed at $T_1$ and $T_2$ , what is the ratio of the new conductivity to the old one of $ADB$
Snow is more heat insulating than ice, because
The area of the glass of a window of a room is $10\;{m^2}$ and thickness $2mm$. The outer and inner temperature are ${40^o}C$ and ${20^o}C$ respectively. Thermal conductivity of glass in $MKS$ system is $0.2$. The heat flowing in the room per second will be