The heat is flowing through a rod of length $50 cm$ and area of cross-section $5c{m^2}$. Its ends are respectively at ${25^o}C$ and ${125^o}C$. The coefficient of thermal conductivity of the material of the rod is $0.092 kcal/m×s×^\circ C$. The temperature gradient in the rod 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

The rate of heat flow through the cross-section of the rod shown in figure is ($T_2 > T_1$ and thermal conductivity of the material of the rod is $K$)

The lengths and radii of two rods made of same material are in the ratios $1 : 2$ and $2 : 3$ respectively. If the temperature difference between the ends for the two rods be the same, then in the steady state, the amount of heat flowing per second through them will be in the ratio

$A$ wall has two layers $A$ and $B$ made of different materials. The thickness of both the layers is the same. The thermal conductivity of $A$ and $B$ are $K_A$ and $K_B$ such that $K_A = 3K_B$. The temperature across the wall is $20°C$ . In thermal equilibrium

Which of the following circular rods. (given radius $ r$ and length $l$ ) each made of the same material as whose ends are maintained at the same temperature will conduct most heat