(a) Figure 11 shows how underground room was ventilated. It had two vents, one at A and the other at B. A fire was lit at point C.

Explain what happened to the ventilation when fire was lit.
(b) Explain how a vacuum flask minimizes loss of heat through radiation.

Answer:

a)
- The air current around C was heated and began to rise up, going out through A. The fresh and cold air came in to replace it through vent B and so the room gets ventilated.
b)
- The double walls are silvered to minimize any radiation.

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(a) Figure 11 shows how underground room was ventilated. It had two vents, one at A and the other at B. A fire was lit at point C.

Explain what happened to the ventilation when fire was lit.
(b) Explain how a vacuum flask minimizes loss of heat through radiation.