current(typically 100 V for 30 minutes). The colored dye in the DNA ladder(molecular weight markers)and DNA samples acts as a"front wave"that runs faster than the dNA itself. When the front wave"approaches the end of the gel, the current is stopped The dNa is stained with ethidium bromide, and is then visible under ultraviolet lightcurrent (typically 100 V for 30 minutes). The colored dye in the DNA ladder (molecular weight markers) and DNA samples acts as a "front wave" that runs faster than the DNA itself. When the "front wave" approaches the end of the gel, the current is stopped. The DNA is stained with ethidium bromide, and is then visible under ultraviolet light