There are many ways this is done. It can be done by having a double walled thermos with either air, an insulator, or a vacuum between. A vacuum will prevent all conduction except where the two walls touch but requires stronger materials.
The thermos flask is basically two flasks, one in side the other, in between the two flasks a vacuum is produced. Convection requires a liquid or a gas to transfer heat, therefore it can't happen in...
It is nearly impossible to let a thermos flask lose heat to its surroundings because, space between the double walls of the thermos flask has been vacuumed, therefore heat has nothing to rely on to...
Thermos flask is a thermos container used to store liquids like any hot drink. The liquid added to thermos flask will retain the temperature even after some time irrespective of external temperatures.