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.
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Air
can be expanded: Negative pressure
Left: The nozzle of this
10-mL syringe was tightly closed by pliers after heating. It contains 0.1
mL of air.
Photo 2: You can
expand this air to a volume of 10 mL by strongly pulling the piston.
If you release the piston
of the syringe it moves back into its old position with a bang.
Photo 3: The upper
closed Liquemin bottle was evacuated by a 20-mL
syringe.
The lower 10-mL bottle is
full of green water. A long hypodermic needlestands in the water -its tip
pointing upwards.
Observation
right:
The green water moves from the lower to the upper bottle in a fountain.
It was sucked upwards by the negative pressure in the Liquemin bottle.
You
make such a negative pressure in your drinking straw while you suck a drink
from the container into your mouth.
back
last modification: 21.03.2002
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