The inside of a vacuum flask is usually coated with silver to reduce heat lost by
Answer Details
The inside of a vacuum flask is usually coated with silver to reduce heat lost by radiation. Heat can transfer from one object to another through convection, conduction, and radiation. In a vacuum flask, there is a vacuum between the two walls of the flask which minimizes heat loss by convection and conduction. However, heat can still be transferred by radiation, which is the emission of electromagnetic waves from a body. The silver coating on the inner wall of the vacuum flask reflects the heat radiation back into the flask, reducing the amount of heat lost to the surroundings. Therefore, silver is used to minimize heat loss by radiation in a vacuum flask.