Question

glide losing energy? What is the working principle of a vacuum flask? Why do we need it? need just 2 ir 3 line answer.​

Answer 1

A vacuum flask, or thermos, does not allow heat transfer by any of the three ways that heat can travel. The silver coating on the inner bottle prevents heat transfer by radiation, and the vacuum between its double wall prevents heat moving by convection. The thinness of the glass walls stops heat entering or leaving the flask by conduction. The case surrounding the flask provides additional insulation.