I chose to capture the tea leaf paradox for the Team Second assignment. This phenomenon is also known as the Inverted Vortex Paradox, and Einstein’s Tea Leaf Paradox, who famously pondered over it and also presented a reasoning for it.
When one normally stirs a liquid, a vortex in the liquid forms that has a dip in the center of the vessel as the liquid is pushed outwards to the walls of the vessels due to centrifugal force (as looking from the non-inertial reference frame of the liquid).
But if the liquid has denser particles in it, or maybe a denser liquid, and the upper liquid is stirred, then instead of forming another vortex by being pushed to the sides of the vessel due to centrifugal force, as one might intuitively expect, the lower liquid instead forms an inverted vortex. But this only occurs if the upper liquid is stirred and not the lower liquid.
To capture this, I utilized blue-dyed distilled water and commonly available paint thinner, clear mineral spirit in this case. Mineral spirit or white spirit being an organic solvent is immiscible with water which is inorganic. The spirit also has a density of approx. 790 kg/m3 and thus floats above the water with a clear interface between the two.
A normal kitchen frother was used for stirring after lowering its power significantly. This helped in the repeatability of the setup.
Images were captured at multiple different settings, but the final image was captured at a high shutter speed due to the fast motion of the fluid and at high f-stops to get a wider depth of field, this combination then required a high ISO of 6400.
Camera Settings for final image:
Camera – Canon EOS 1500D
Lens – Kit 18mm – 55mm
Focal Length – 55mm
Shutter Speed – 1/2500
Aperture – f/36
ISO – 6400
Resolution – 6000×4000 (Original), 5947×3958 (Edited)
Edited on Darktable
Video of the demonstration:
The report can be accessed below: