I'm told at school that the Electromotive Force (e.m.f) of a battery equals the potential difference between the terminals of the battery when there is no current.

How is that possible? How can there be a potential difference with no charge flowing?

Thanks.

I'm told at school that the Electromotive Force (e.m.f) of a battery equals the potential difference between the terminals of the battery when there is no current.

How is that possible? How can there be a potential difference with no charge flowing?