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Suppose we have two resistor and let A,B,C be points across resistors.Va-Vc=Va-Vb+Vb-Vc.Thus pd across the resistor combination can be obtained by simply adding the individual pds across each resistor.But for this we should have a common point(in this case b) for two resistor and this is not found in cells as adjacent cells have opposite polarity and hence different potential so how we can simply add the individual emfs.Please explain.

Edit If current move from -ve to +ve terminal of a cell certainly work is done but as it goes forward it comes to -ve terminal of adjacent cell and hence work should be obtained.Why PD b/w +ve of one and -ve of adjacent is not counted?

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    $\begingroup$ Welcome to Physics SE! Could you possibly clarify your question with a diagram of sorts? $\endgroup$ – Alex Robinson Oct 25 at 16:03
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    $\begingroup$ Alex is right. To difficult to follow this without a circuit diagram. $\endgroup$ – Bob D Oct 25 at 19:27
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The electric potential difference between two points is a measure of how much work is needed to move a unit charge from one point to the other. (The work may be positive or negative.) If you are crossing circuit elements in series, you do work to cross one, and then more work to cross the next.

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  • $\begingroup$ If current move from -ve to +ve terminal of a cell certainly work is done but as it goes forward it comes to -ve terminal of adjacent cell and hence work should be obtained.Why PD b/w +ve of one and -ve of adjacent is not counted? $\endgroup$ – Sharad Oct 25 at 19:29
  • $\begingroup$ Work is done on a charge by a battery (or power supply) to increase its potential energy, and work is done by the charge when goes through a circuit element where it looses potential energy. Potential differences are scaler quantities which add or subtract. What do you mean “its not counted”? $\endgroup$ – R.W. Bird Oct 26 at 22:16
  • $\begingroup$ I think I finally understand what you are asking. If you connect two batteries in series, with the + terminal of one battery connected to the – terminal of the other why is there not a potential difference between those two terminals? If you connect the the two terminals with a short piece of heavy wire there will be no significant voltage drop on that wire. Keep in mind that the + and – designations on the terminals just indicate the direction in which the battery will pump electrons. They do not indicate a voltage relative to an external reference point. $\endgroup$ – R.W. Bird Oct 28 at 14:30
  • $\begingroup$ So you mean to say that the -ve terminal of one battery and + ve terminal of adjacent would be at same electric potential?But how can this be as one has negative and other positive potential creating a difference? $\endgroup$ – Sharad Oct 28 at 19:29
  • $\begingroup$ The potential at the terminals of a battery in a circuit depends on your choice of a reference point and the location of the battery in the circuit. Both terminals may be positive or negative relative to the reference point. (Any measure of potential energy depends on the choice of a reference point.) $\endgroup$ – R.W. Bird Oct 29 at 14:05

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