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The title itself seems silly to me but here is this question,

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A constant electric force of $8\ \text{N}$ acts in the direction shown and constant non electric force of $10\ \text{N}$ acts rightward, above picture is a battery.
The questions asked were EMF of cell potential difference across terminals and internal resistance of cell. I think the emf is produced due to non electric force which I guess is due chemical reactions, so answer should be $10 \times 0.1 = 1\ \text{V}$. Now what about potential difference What I think is the net work done across terminals is potential difference, it comes out to be $0.1 \times 2 = 0.2\text{V}$, there is no option for $0.2$, how can this be? And without P.D. I cannot find internal resistance, what concepts am I missing?

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  • $\begingroup$ Maybe my title was misleading , I just wanted to ask what am I getting wrong towards the end of my question, please read. $\endgroup$ – ADITYA PRAKASH Jul 12 at 4:54
  • $\begingroup$ Following on from your analysis of the situation you would evaluate the potential difference across the terminals of the battery to be zero when there is no current flowing through the battery. $\endgroup$ – Farcher Jul 12 at 5:55
  • $\begingroup$ Actually yes , my analysis would've done , so considering an open circuit the force on charge by battery is equal to the opposite of the force of electric field due to the charge buildup.so at all points along g the terminals net force is 0 , therefore no energy is being provided to a charge by battery , but when I connect external circuit the charge buildup is somewhat reduced and electric field is weakened , then battery force restarts its work while whatever electric field is left causes terminal voltage, am I correct now ? $\endgroup$ – ADITYA PRAKASH Jul 12 at 6:04
  • $\begingroup$ Potential difference (voltage) does not equal work (Joules). It is work per unit charge (Joules per Coulomb) to move the charge between two points. $\endgroup$ – Bob D Jul 12 at 12:42
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What I think is the net work done across terminals is potential difference, it comes out to be 0.1×2=0.2V, there is no option for 0.2, how can this be? And without P.D. I cannot find internal resistance, what concepts am I missing?

Consideration of the equivalent circuit of a battery shown below may help you.

Which of the two forces in your diagram do you think is associated with the battery’s emf (its internally generated voltage)?

Which of the two forces do you think is associated with the voltage that is across the battery terminals, when current is flowing to the circuit?

Finally, what force do you think is associated with the work required by the battery to overcome its internal battery resistance in order to deliver current to the circuit?

If you can answer these questions, you should have your answer.

Hope this helps.

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