If I run a small agarose DNA gel and use a voltage of 90V, the DNA migrates the length of the gel in about an hour. If I use a medium size gel I have to use a voltage of 140V to move the same DNA the same distance (the equivalent of the small gel) in the same amount of time. For a large gel it takes about 170V. What is it exactly that requires a higher voltage to maintain the same speed of DNA movement?
I think this is more of an electrochemistry question than a biology questions so I put it here.