How can you “see” the electric field strength lines?

Tension lines are just a technique for graphing fields. They help to visualize the picture of the field in space. However, they can be made “visible”. We put small grass seeds (or semolina) into a cuvette with a transparent viscous liquid, such as castor oil or glycerin. The seeds are randomly distributed over the surface of the liquid. We will place charged bodies there – two oppositely charged balls. Near these bodies, the seeds line up in chains along the field strength lines.