How a barometer works

Misr

What makes mercury rise in the tube?Does atmospheric pressure carries the mercury in the tube?Is that true?

DaveC426913

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.

Misr

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

Danger

Right. That's also why you can drink through a straw.

Misr

Ok thanks