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TEST KEEP CLOSED

THERMAL PROPERTIES OF MATTER

Thermal Expansion

Thermal Conductivity

Balloon in Evacuated Bell Jar (Model Lung)

This demonstration illustrates the pressure differences involved in the process of breathing. A balloon is attached to one end of a piece of tubing which extends through a stopper in the top of the bell jar. The interior of the balloon remains at atmospheric pressure. The pressure surrounding the balloon is reduced by opening a valve from the bell jar to a vacuum pump. As the pressure drops in side the bell jar, the balloon expands and fills with air from the room. The process can be reversed by closing the valve to the pump and opening a vent valve. In the actual breathing process, the pressure changes are achieved by the action of the diaphragm, which changes the shape and volume of the chest cavity.

Balloon in Evacuated Bell Jar (Model Lung)