How do Vacuum Flasks Keep Things Hot?

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A vacuum flask keeps things hot for several hours because it stops heat from escaping as far as possible. It is designed to prevent heat loss. The silver walls of the container inside the flask reflect heat rays back into the container. There is also a vacuum between the walls of the container to stop heat from flowing through the walls. The container is surrounded by an outer shell made up of insulating material that decreases the loss of heat. The flask, thus, loses very less heat and keeps hot for a long time.

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