A clean glass tube of radius 0.35 mm stands in water…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A clean glass tube of radius stands in water. How high does the water rise? How high would it rise in a tube of twice the radius? (Surface tension , angle of contact , .)
Need a reminder? The key ideaShow
Capillary rise: , where is the angle of contact. A liquid that wets the tube () rises; one that does not () is pushed down.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. .
Step 2. Twice the radius, half the rise: .
Answer: ; .
Check. The weight held up, , doubles in the wider tube, just as the edge length doubles.
Watch out. The radius must be in metres: .
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