How does heat transfer by radiation conduction and convection?

Answer 1

A thermos is able to do what it does by using a several of physical and material properties to keep our Hot Chocolate hot and our ice tea icy.
A thermos has an inner container made of glass. This container is really like one bottle inside of another bottle and sealed at the ends by melting the edges together. The air is removed out from the space between the two bottles to produce a vacuum, which is not a good conductor of heat and does a good job at slowing down the movement of heat. To slow down the other heat they coat the facing surfaces of the glass bottles with a silvery coating (like a mirror). This reflects the heat and helps slow down any losses that might get that way. They use a material like cork or rubber to make the bottle stopper and anything else that might touch the outside surface of the glass container. These materials are bad conductors of heat and slow down the heat loss. What's left is what we can see on the outside which can be metal or plastic and is the covering for the glass bottles.
The idea here (with the thermos) is to slow down the movement of heat from one place to the other. So if you have hot stuff in the thermos or cold stuff in the thermos, the end result is the same. Keep heat from moving to where you don't want it to go for as long as possible.

NB It's worth mentioning that modern vacuum flasks (Thermos being a trade name) are made almost entirely of stainless steel, inside and out - it doesn't shatter and is naturally reflective, although not polished to a mirror shine when used as a flask inner. Modern stoppers are also made of plastic.

Answer 2

a thermos limits heat transfer through the walls of the thermos. that lets the fluid inside the thermos keeps its temperature nearly constant for a long period of time (whether the temperature is hot or cold).

Answer 3

A thermos bottle prevents heat transfer to the outside by using a vacuum between the walls of the bottle.

The innerwall is usually made of glass while the outside wall is made of a plastic.

Metal walls also exist.

A vacuum doesnt conduct, since you need a substance to conduct heat.

Same goes for convection, warm and cold liquids / gasses can rise and drop all they want, but the heat cant be passed on to the outside wall.

Radiation is prevented by using reflective surfaces, which bounce back into the substance you are carrying in the bottle.

Answer 4

Conduction- when heat is transferred through physical contact, eg, when you touch a hot plate.

Convection- when heat is transferred through some media (like air). eg. a Heater heating a room.

Radiation- when heat is transferred through vacuum. eg.Heat from Sun travels through vacuum in space to reach earth.

Answer 5

Some heat exists in the form of molecular kinetic energy, while some of it exists in the form of electromagnetic radiation. The metallic inner surface acts as a mirror to reflect the electromagnetic radiation back into the container.

Answer 6

thermos flask controls 2 heats through: * conduction - prevented through the vacuum * radiation - prevented through the silvered surfaces

Answer 7

Thermos bottle use insulation (usually air) preventing conduction heat transfer to surface. Without heat conduct to surface, there is no heat loss through surface convection.

Answer 8

A "thermos flask" will have neither conduction nor convection,

thus all heat loss is by radiation.