why is it said that current flows from highar potential to lower potential in a circuit?
Protons of an atom don’t take part in conduction of electricity.
Accumulation of electrons in the negative terminal of a battery creates a negative potential (low potential), and the deficiency of electrons in the positive terminal creates a positive potential (high potential). Hence, electrons flow from low potential to high potential; but current as we know flows from high to low potential.
Flow of current is not the flow of positive charge or protons. It is a convention that has been followed since the discovery of electric charge, that current flows from high potential to low potential.
Thus, we conclude that in a circuit current flow from high potential to low potential and electrons flow from low potential to high potential.
The direction of current that we follow is actually a convention which has been followed for centuries. Flow of electrons constitutes current. And in a battery the negative terminal has accumulation of electrons not the positive terminal.