A negative charge is surrounded by four positive charges. They are all of the same strength. The electric field lines are plotted below. I am looking for the property of the drawn 'red lines' that originate from the negative charge.
Is there anyway that I can explicitly find the lines that originate from the center negative charge, and divide each pair of neighboring positive charges? (e.g. for the top-left and bottom-left chargers, they each has an electric field line bending to the left, and a neighboring electric field line that ends at the negative charge. I need to find the 'red line' such that divide the space between the two electric lines pointing left equally, as well as the space between the two electric lines pointing to the negative charge)
Also, when the charges are of different strength, the 'red lines' will change to curves, and what will the properties of these curves be?