What is the difference between "potential difference" and "electromotive force" in a cell?

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Potential difference is a value you measure between two points in a conductor. It is the cause of a current flowing in your circuit. Suppose you have a resistance `R` with current `I` passing through it. With the variables given, you can calculate the potential difference between the terminals of...

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Potential difference is a value you measure between two points in a conductor. It is the cause of a current flowing in your circuit.

Suppose you have a resistance `R` with current `I` passing through it. With the variables given, you can calculate the potential difference between the terminals of your resistor. Just use the following formula:

`V = RI `

So, generally, potential difference is a dependent variable - because it depends on other variables that you can potentially measure.

Now, electromotive force is an independent variable. You can't solve it in terms of other things in your given system (actually, that's not entirely true, but we're assuming that). Just look at the outlet of your house--it probably gives out a voltage of around 220V. It does not depend on the resistance of your circuit. So its electromotive force is 220V. With it, we can calculate the current going through a resistance connected to it. See the difference?

You can think of electromotive force as the ability of a source (say a battery) of generating currents in your circuit.

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