The temperature gradient in a rod of length $75 \ cm$ is $40^{\circ} C/m$. If the temperature of the cooler end of the rod is $10^{\circ} C$,then the temperature of the hotter end is: (in $^{\circ} C$)

The temperature of the hot and cold ends of a $20 \ cm$ long rod in a thermal steady state are at $100^\circ C$ and $20^\circ C$ respectively. The temperature at the centre of the rod is ...... $^\circ C$.

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:

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

$A$ rod of length $50 \, cm$ has one end at $25^oC$ and the other end at $125^oC$. The temperature gradient is ....... $^oC/cm$.

For heat to flow from one end to the other in a solid,it is necessary to have: