if electromotive force is the potential difference between two points
but also the voltage is the work done per each charge to move from a place to another
then doesn't higher emf mean more work?
how come it means higher charge flow ?
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$\begingroup$ "if electromotive force is the potential difference between two points" - it isn't. $\endgroup$– Alfred CentauriCommented Sep 22, 2017 at 20:44
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2 Answers
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There appears to be a couple layers of misunderstanding here so I'll try to clarify. Similar to what you stated, a difference in potential between two points, can be defined according to the work that an electric field would do on a given charge, $q$, by displacing it between those two points. So we have, \begin{align} \Delta V = \frac{W}{q}. \end{align} So a higher $\Delta V$ does mean that a charge that traverses that potential will have more work done on it BUT the $\Delta V$ only requires the existence of an electric field, no charge to move through it is required. If there is a field, the potential will be there, they are different representations of the same thing and the above is a quite a general definition.
Now, I'm guessing your confusion then comes from \begin{align} V=IR. \end{align}
The thing is that this relationship is not general at all, and only applies to ideal resistors (as Alfred Centauri points out), so you can't just equate this with the first definition. In the first definition the charge was just a construct you use to relate $\Delta V$ and $W$. Here you're talking about the amount of current, $I$, resulting from putting a potential difference, $V$, on a resistor with some resistance, $R$.
As for why it happens that greater $V$ means greater $I$ you can think of turning up the pressure on a water hose. The length of hose has some ''resistance" but by turning up the pressure you can get more ''current."
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$\begingroup$ "and only applies to circuits" - to be sure, it only applies to (ideal) resistors. It doesn't apply to, for example, a circuit consisting of a voltage source and a capacitor (or an inductor or a diode etc.). $\endgroup$ Commented Sep 22, 2017 at 22:08
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if electromotive force is the potential difference between two points
Potential has units of energy which is force times distance.
but also the voltage is the work done per each charge to move from a place to another
OK, that sounds reasonably standard. Potential is measured in units volts and potential differences can be measured with test charges of calibrated charge.
then doesn't higher emf mean more work?
If the same charges were moved the same distance under condtions of higher EMF, then there would have been more work done.
how come it means higher charge flow ?
Now you are asking a question about material which you have not referenced.
