passwella.
Menu

JAMB Physics 1987 Question 25

Question 25

Heat Transfer

The vacuum in a thermos flask helps to reduce heat transfer by

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

Answer: B (convection and conduction)

Explanation

Conduction and convection both need a material medium, so a vacuum stops them. Radiation is reduced by the silvered walls instead.