# Does a higher e.m.f give a larger current?

I was told that e.m.f. is the work done on the charge carriers (i.e. electrons in wires or free ions in electrolytes).

Does this mean that e.m.f is preportional to current (the rate of flow of charge) such that a higher e.m.f. of a power source provides a higher current?

Yes. EMF is basically just a voltage. The higher the EMF, the more current, assuming a constant resistance.

• Oh right, so to explain, a higher EMF means a larger potential difference hence the charge carriers move faster to the opposite polarity of the cell, so the current is higher? – vik1245 Mar 23 '17 at 22:20
• Yes, that's correct, although current is just defined as charges across some cross-sectional area per time, so you could achieve a higher current from the charge impulse crossing that area more quickly, or from more charge impulses moving at the same speed as before. The answers to this question are very thorough and might help you conceptually even more: physics.stackexchange.com/questions/90471/… Hope this helps! – smelborp Mar 23 '17 at 22:28
• thanks very much! I'll answer my question! Upvote me please! Thanks. – vik1245 Mar 23 '17 at 22:30

Only if the resistance is fixed. If the resistance is variable, then the current may vary. Though EMF is directly proportional to current, resistance is what opposes it as per the ohm's law. Of course, other conditions like standard pressure and temperature should remain constant. They affect the resistance as well.

• Indeed! I updated my answer to respond to what you have written! – vik1245 Mar 23 '17 at 22:37

A higher e.m.f. means a larger potential difference.

Hence, the charge carriers move faster to the opposite polarity of the cell, so the current is higher. (This is given as current is defined as the rate of flow of charge per unit time)

This is only given if the resistance is constant of course, and the temperature does not change.