On what basis does gel electrophoresis separate dna segments

Gel electrophoresis is a technique used to separate DNA macro-molecules or fragment base on their size and charges. During separation, the DNA fragment will travel through the gel in different direction and at different speed base on their size and charges. However, the movement of nucleic acid in gel is usually influenced by size and conformations, gel concentration, buffer conditions.

equal distribution i think.

where is the scientific experiment?