Science · 6 pages · 12 min
How a thermos slows heat
A vacuum gap and mirrored walls block conduction, convection, and much of the radiation.
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From the opening
A thermos slows heat by putting a vacuum between two walls, so almost no air is left to carry energy by conduction or by convection. Mirrored walls cut the radiation that would otherwise cross that empty gap. The opening covers why the gap is pumped out, what the mirror does to radiation, and leaks through the stopper and neck.
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Inside
- Why the gap is pumped out
- What the mirror does to radiation
- Leaks through the stopper and neck
- How foam insulation differs
- Where the idea stops applying
- A distinction worth keeping
Sources
- The Dewar vacuum flask
- Conduction, convection, and radiative transfer