negative potential

If you recall your engineering, Potential at a point is defined as the work done to move a charge from infinity to the point. Since infinity never exists, all our definitions are actually potential differences.

So any potential you measure is always with respect to a reference. So whether there is positive potential or negative potential is with respect to a reference.

So strictly speaking there is no absolute negative or positive potential. Electrons always flow from a lower potential level to a higher potential level, and both of these could be positive based on your reference.

-Karthik
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