What is Vacuum flask?
{{More sources}}[[File:Dewargefäß Deutsches Museum.jpg|thumb|upright|Laboratory Dewar flask, [[Deutsches Museum]], Munich]] [[File:Vacuum Dewar Flask.svg|thumb|upright|Diagram of a vacuum flask]] [[File:Liquid nitrogen tank.JPG|thumb|upright|A [[cryogenic storage dewar]] of [[liquid nitrogen]], used to supply a [[Cryopreservation|cryogenic freezer]]]] A '''vacuum flask''' is a special container that is designed in such a way that [[heat]] cannot easily enter or exit. That way, hot [[drink]]s are kept hot longer, and cold [[food]] is kept cold. The flask is made of two containers which are separated. Between the containers there is [[vacuum|almost no air]], so heat does not pass easily.the flask is also know as '''dewar flask''' after it's inventor.<ref>{{Cite web|title=James Dewar's vacuum flask {{!}} Royal Institution|url=https://www.rigb.org/explore-science/explore/collection/james-dewars-vacuum-flask|access-date=2022-12-06|website=www.rigb.org|language=en}}</ref> [[Sir James Dewar]] invented the flask in 1892. It consists of two [[wiktionary:flask|flask]]s, placed one within the other and joined at the neck. The gap between the two flasks is partially evacuated of air, creating a near-[[vacuum]]. This significantly reduces heat transfer by [[heat conduction|conduction]] or [[convection]]. When used to hold cold liquids, this also eliminates most condensation on the outside of the flask. In the household, vacuum flasks are used to keep [[beverage]]s hot or cold for longer periods of time, and for keeping cooked food hot. They are also used for [[thermal cooking]]. Vacuum flasks are also used for many purposes in industry. == References == {{reflist}} {{stub}} [[Category:Containers]] [[Category:Laboratory equipment]]