The difference of temperature in a material can convert heat energy into electrical energy. To harvest the heat energy,the material should have

The radius of a conductor increases uniformly from the left end to the right end as shown in the figure. The material of the conductor is isotropic,and its curved surface is thermally isolated from the surroundings. Its ends are maintained at temperatures $T_1$ and $T_2$ $(T_1 > T_2)$. If,in a steady state,the heat flow rate is equal to $H$,then which of the following graphs is correct?

Four rods of silver,copper,brass,and wood are of the same shape. They are heated together after wrapping a paper on each. The paper will burn first on:

$A$ thermocouple is an arrangement of two different metals to :-

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

Ice starts forming in a lake with water at $0^{\circ}C$ when the atmospheric temperature is $-10^{\circ}C$. If the time taken for $1 \; cm$ of ice to form is $7$ hours,then the time taken for the thickness of ice to change from $1 \; cm$ to $2 \; cm$ is: