If the ratio of coefficient of thermal conductivity of silver and copper is $10 : 9$ , then the ratio of the lengths upto which wax will melt in Ingen Hausz experiment will be
$6:10$
$\sqrt {10} :3$
$100 : 81$
$81 : 100$
Temperature of water at the surface of lake is $ - {20^o}C$ Then temperature of water just below the lower surface of ice layer is ...... $^oC$
If the radius and length of a copper rod are both doubled, the rate of flow of heat along the rod increases ....... times
The coefficient of thermal conductivity of copper is nine times that of steel. In the composite cylindrical bar shown in the figure. What will be the temperature at the junction of copper and steel ....... $^oC$
One likes to sit under sunshine in winter season, because
Two metal rods $1$ and $2$ of same lengths have same temperature difference between their ends. Their thermal conductivities are $K_1$ and $K_2$ and cross sectional areas $A_1$ and $A_2$ , respectively. If the rate of heat conduction in $1$ is four times that in $2$, then