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JAMB Physics 2008 Question 25

Question 25

Heat Transfer

In a good thermos flask, the main cause of heat loss is

  1. A.conduction through the cork.
  2. B.the plastic base of the thermos flask.
  3. C.the silvered walls and shiny metals.
  4. D.the outer cover or jacket.
Show the answer and explanation

Answer: A (conduction through the cork.)

Explanation

The vacuum stops conduction and convection through the walls and the silvering cuts radiation, so most of the heat that still escapes is conducted through the cork stopper.