A thermos flask has a double-walled glass container with the space between the walls…
PHYSICS · Single correct · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter
Problem
A thermos flask has a double-walled glass container with the space between the walls evacuated, and the inner surfaces facing the vacuum are silvered. Which statement best explains how this design reduces all three modes of heat transfer between the hot liquid inside and the surroundings?
(a) The vacuum reduces radiation and convection, while the silvered surfaces prevent conduction
(b) The vacuum cuts off conduction and convection, while the silvered surfaces reflect thermal radiation back toward the liquid
(c) The silvering eliminates conduction and convection, while the vacuum reflects thermal radiation
(d) The silvered surfaces reflect radiation, while conduction and convection are minimised by the low thermal conductivity of the glass walls, not by the vacuum