How does gel electrophoresis determine relatedness in a species?

Gel electrophoresis is used in a device that compares the DNA of organisms to each other.

When gel electrophoresis is used, bands of DNA are pulled to polar ends, creating a line of bands of DNA varying in thickness. Some bands may attract more than others which then makes this line of DNA bands. This occurs with several samples of DNA used in a device with gel electrophoresis. The lines of bands that are the most similar are the ones that are the most related to each other. If the line of bands is identical to another line of bands, it is the same organism. 

-E :)

The name of the instrument that the scientist uses is called a microscope.a microscope is used to view objects which is not visible to the naked eyes