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JAMB Physics 2000 Question 22

Question 22

Heat Transfer

The main reason for making the cover of a vacuum flask airtight is to prevent heat loss by

  1. A.conduction
  2. B.evaporation
  3. C.radiation
  4. D.convection
Show the answer and explanation

Answer: D (convection)

Explanation

The airtight stopper stops warm air (and vapour) from circulating out of the flask, so it cuts heat loss by convection; radiation is reduced by the silvered walls, not the cover.