Describe the Thermos Flask?
Answer / amita sharma
Thermos Flask:-It consists of a double walled glass bottle with silvering on the inner side of each wall. The air from the space between the walls is evacuated by an air pump through a very small tube at the bottom which is sealed when the air has almost been sucked while the pump is in operation. The bottle is placed in side a metallic container, there being bad conductors of heat like cork pieces or felt pads between the two. Any substance, hot or cold, put inside the flask remains so for a considerable period as
(i)There is almost no possibility of exchange of heat due to radiation because of the silvering of inner sides of both of its walls which reflect back the heat
(ii)There is no exchange of heat due to conduction as the space between the walls is evacuated and bad conductors of heat are placed between the flask and the metal container an d
(iii)The exchange of heat due to convection is also not possible as there is no medium between the walls of the flask
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