How about the PD produced by diffusion across a semiconductor NP junction?
Also the 'electro-negativity' driven diffusion with thermocouples and
Galvani's metal frog-stickers?
Seebeck Effect? (flip side of the Peltier Effect.)
All this MIGHT boil down to the Pauli Exclusion Principle that isn't a force?
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Chuck Britton Education is what is left when
britton@ncssm.edu you have forgotten everything
North Carolina School of Science & Math you learned in school.
(919) 286-3366 x224 Albert Einstein, 1936