为什么保温瓶能长时间保温？
Why does a thermos keep drinks hot or cold for a long time?
保温瓶有双层真空壁，真空几乎不传导热，加上镀层反射辐射，所以内外热量很难交换，温度就保得住。
A thermos has a double wall with a vacuum between layers; the vacuum blocks conduction and the reflective coating reduces radiation, so heat barely transfers in or out.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#保温 #真空 #热传导
保温杯的真空夹层挡住了哪些传热通道?镀银内壁又是在对付剩下哪一种散热方式?
Which heat-transfer channels does the vacuum gap of a thermos flask block, and what remaining loss mechanism do the silvered walls target?
双层壁之间的真空同时切断了空气对流和气体分子碰撞导热,这两条通常是日常容器最主要的散热途径。剩下的主要是红外辐射,而内外壁银膜的发射率极低,能把大部分热辐射反射回原侧。瓶口的软木或泡沫塞导热系数很小,再补上最后一条沿固体接触漏热的通道。
The vacuum between the double walls cuts off both air convection and gas-molecule conduction, normally the dominant losses from an everyday container. What remains is chiefly infrared radiation, and the low-emissivity silver films on both walls reflect most of it back to its own side. A cork or foam stopper at the mouth, with its small conductivity, closes the last path of leakage through solid contacts.
难度 进阶 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：此条未指向带版次的可引用著作（通识性内容、机构文件或未展开的英文书名），本库不提供独立书目出处；如需精确引用，需由编辑补全具体篇目与版次。
Stefan J., Sitzungsber. Kais. Akad. Wiss. Wien 79, 391–428 (1879);Boltzmann L., Annalen der Physik 22, 291 (1884);Burger R., 美国专利 US 872,795:Double-walled vessel with a space for a vacuum between the walls (1907)
Stefan J., Sitzungsber. Kais. Akad. Wiss. Wien 79, 391 (1879); Boltzmann L., Ann. Phys. 22, 291 (1884); Burger R., U.S. Patent 872,795, Double-walled vessel with a space for a vacuum between the walls (1907)
#传热与隔热 #杜瓦真空瓶
为什么黑夜比白天冷？
Why is night colder than day?
白天地面吸收阳光积热，夜里没有日照又向天空散热。
Ground stores daytime heat but radiates it away with no sun at night.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#辐射 #昼夜 #温度