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How a barometer works

  1. Oct 16, 2011 #1
    [PLAIN]http://www.barometerplanet.com/wp-content/uploads/2009/09/merc_barometer.jpg [Broken]

    What makes mercury rise in the tube?Does atmospheric pressure carries the mercury in the tube?Is that true?
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Oct 16, 2011 #2


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    Think about what would happen if the whole thermometer were in vacuum. The mercury would have no reason to climb the tube; it would just pool at the bottom. Vacuum inside, vacuum outside.

    Now, push down a little bit on the mercury outside the tube. It's going to rise up the tube a little.
    Last edited by a moderator: May 5, 2017
  4. Oct 17, 2011 #3
    Yeah,so air pushes on the mercury in this basin,(or whatever it is called)and the mercury in turn pushes up on the mercury of the tube
  5. Oct 17, 2011 #4


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    Right. That's also why you can drink through a straw.
  6. Oct 20, 2011 #5
    Ok thanks
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