I've always had trouble visualizing what voltage is, and how it relates to other electric concepts that are easy to visualise such as the colomb or the amp. The best I can guess is that voltage is the difference between two charge densitys, therefore voltage is measured in charge/volume but I don't think that's true. Can anyone help? I could post a dump of my mind's rambling internal dialogue on this problem but I hope that's not necessary to clarify what I mean. Search engine for "charge density voltage" haven't helped me much. This is in the atomic forum rather than classical because I find it useful and preferable to visualise at the atomic level in case you need a reason.