Draw a labelled diagram of a thermos flask. Explain how the transfer of heat by conduction, convection and radiation is reduced to a minimum in it.

Labelled diagram of a thermos flask is shown below:

The vacuum present between the walls of the bottle prevents transfer of heat by conduction and convection. The shining surface on the outer side of the inner wall and inner side of the outer wall reduces the transfer of heat by radiation. The cork stopper prevents the transfer of heat by convection. In this way the transfer of heat by conduction, convection and radiation is reduced to a minimum in it.