Making Barometers

CCA! Volume 5

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Making Barometers

Mercury barometers are constructed so that they can be used to determine and compare vapor pressures of liquids. The barometers read 736 mmHg.


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Voiceover
Pressure exerted by a vapor can be measured using barometers. Mercury is poured into a dish below three barometer tubes. A vacuum pump is used to create a vacuum at the top of each tube, and draw the mercury into it. When the tube is evacuated, the valve is closed. Here the height of the mercury in each tube is 736 millimeters.

Discussion
Three barometers are constructed by evacuating vertical glass tubes whose lower ends are below the surface of a pool of mercury. The three barometers read 736 mmHg.

Design, Demonstration, Text and Graphics:
	Kristin Johnson	University of Wisconsin - Madison, Madison, WI 53706

Voice:
	Michael Killips	University of Wisconsin - Madison, School of Nursing, Madison, WI 53706

Video:
	Jerrold J. Jacobsen	University of Wisconsin - Madison, Madison, WI 53706