Page 235 - Primary Five Science

The Vacuum Flask

A vacuum flask keeps

hot things hot and cold

things cold.

The silver coating on the

inner bottle prevents
heat transfer by radia-

tion, and the vacuum be-

tween its double walls

prevents heat moving by

convection. The thinness

of the glass walls stops

heat entering or leaving

the flask by conduction.

 Cork or Stopper

It prevents heat loss by

conduction

 Vacuum

It prevents heat loss by conduction. It also prevents heat gain

by convection

 Metal case or Casting

It protects the double walled glass

 Cup or top cover (green in picture)

It is used to take what is put in the flask

 Double walled glass

These are silvered to reflect heat