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In the above circuit, two cells are connected in series to an external resistance $R$. Now the current going from point $A$ must return back to point $B$ of the cell. But for that it has to pass through $DC$ path. We all know current flows from higher potential to lower potential. But here potential of $D$ is less than the potential of $C$ since $C$ is the positive end and $D$ is the negative end of the battery. How is this possible?

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  • $\begingroup$ Current doesn't always flow from high to low potential, as your circuit illustrates. See this answer. $\endgroup$
    – Puk
    Commented May 4, 2022 at 22:49
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    $\begingroup$ If you want to learn this stuff, you really should get a couple of cells, a resistor, and a multimeter (to measure the potentials). Without a base in reality, paper reasoning yields limited insights. You don't want to wind up like the MIT students unable to power a light bulb: youtube.com/watch?v=aIhk9eKOLzQ $\endgroup$
    – John Doty
    Commented May 4, 2022 at 23:20
  • $\begingroup$ Why are you limiting your concern for current going from D to C when it also goes from B to A to complete the loop? $\endgroup$
    – Bob D
    Commented May 5, 2022 at 13:21

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Charge flows from a point at which its electrical potential energy (EPE)is higher to a point at which its EPE is lower if electrostatic forces are the only forces (apart from resistive forces) acting on the charges. This is the case in the part of the circuit outside the battery. But inside the battery, in the vicinity of the electrodes, it is not the case because chemical forces also act. These urge the charges in in a direction such that their EPE increases.

[I've avoided talking in terms of potential so as not to have to choose 'higher' and 'lower' according top the sign of the moving charges.]

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  • $\begingroup$ To use a crude analogy: the battery acts like a pump, forcing electrons "uphill", because there are chemical reactions that are energetically favorable but can only happen (or happen much, much faster) if those electrons are, indeed, going "uphill". $\endgroup$
    – TimWescott
    Commented May 4, 2022 at 23:28
  • $\begingroup$ The electrons are actually going "uphill" outside the battery. They go from lower potential to higher potential under the action of an electric field. But the discussion of circuits is done usually in terms of conventional, positive charges. The positive charges go downhill outside the battery and uphil inside the battery. $\endgroup$
    – nasu
    Commented May 5, 2022 at 2:53

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