Gel electrophoresis model

[Stephen R. Laniel]

While doing a simple electrophoresis demonstration using agarose gel and phage lambda DNA, two questions 
popped into my head.  First, given a certain mass of a DNA fragment, what is the minimum voltage required to make 
that mass move?  Similarly, given a certain voltage, what is the maximum mass that will move because of attraction to 
the electrode?

Perhaps this is more of a physics question than a biology one; if so, I apologize and will repost it to the appropriate 
newsgroup.  If, however, anyone can help me answer this question, it would really help.  Thanks a lot.

--Steve

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Stephen R. Laniel    | "Levin wanted friendship and got friend-
---------------------| liness; he wanted steak and they offered
slaniel at together.net | Spam" -- Bernard Malamud