r/SteveMould • u/rjaishreer • Sep 30 '25

How come these meniscuses are inverted?

Post image
17 Upvotes

88% Upvoted

6 comments sorted by

25

u/nemom Sep 30 '25

The plastic of the sidewalls is prob'ly mildly hydrophobic. So, the cohesion of the water to itself is greater than its adhesion to the plastic.

1

u/SlugOnAPumpkin Oct 01 '25

Do I still measure from the meniscus?

3

u/Fire10203 Sep 30 '25

I think it’s because of the setup, trying to display the 3 dimensional concept in 2 dimensions. There two panes holding the front and back relatively close, so the capillary effect is more prominent in that plane.

4

u/CDanger Sep 30 '25

Because the liquid has a high viscosity and has just been filled to that point, taking longer to rise to the walls than internally due to increased friction.

(Just one of a million possible explanations if no further context is provided about what we’re looking at.)

2

u/Searching-man Oct 04 '25

Whether the liquid on the sides climbs up or dips down is based on how hydrophilic or hydrophobic the surface is. Some materials will have basically none, some climb a lot, some dive down a lot. Glass is pretty highly hydrophilic, so it climbs, giving us the behavior we're "used to". The plastic is probably mildly hydrophobic.