Many students are fascinated by the seemingly magical operation of hummingbird feeders and wonder why the sugar water does not pour out of the access ports when the feeders are hung upside down.

1.
There are plenty of YouTube videos describing the card-and-water glass trick. Here is an amusing variation that mixes a little magic with the demo
: https://www.youtube.com/watch?v=IZg1J3ibZ7E.
2.
J. W.
van Honschoten
,
N. R.
Tas
, and
M.
Elwenspoek
,
“The profile of a capillary liquid bridge between solid surfaces
,”
Am. J. Phys.
78
,
277
286
(
2010
).
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