Relevant Resource Questions :

Concepts demonstrated :

• thermal insulation
• conduction
• convection

Click on the picture to see a second picture

• evacuated window

• Plug light into powerpoint

Physics involved :

The evacuated window prevents both conduction and convection occuring resulting in a window that is very good as an insulator.
Typical best results quoted for the heat loss through the best conventional double glazed window is about 0.6 W/m2. The theoretical best performance of this window is 0.1 W/m2.

How to use the Demonstration :

• Show the demonstration to the students when discussing conduction and convection.
• Pose such questions to the students as to how they might reduce the problems of conduction and convection.
• Discuss the difference between normal windows, double glazed windows and evacuated windows.

• thermos flask

Other Comments :