In what circumstances might it be important to use gel electrophoresis to separate and identify plasmids and short linear pieces of dna?

I believe using gel electrophoresis to separate and identify plasmids and short linear pieces of DNA would be important if one is making a recombinant plasmid and has to verify that he/she has been successful. Gel electrophoresis is a technique that is used to separate mixtures of DNA, RNA, or proteins according to molecular size. The molecules being separated are pushed by an electrical field through a gel that contains small pores.