Consider the given charged line, twisted into a square shape with four sides, 1,2,3,4 in the x-y plane, of side length L.
a) Find, using symmetry, the direction of the electric field at point P above the center of the square. (hint, how do the fields due to the four sides add up?)
b) What is the electric field at point P due to side 1? Express it in terms of its x and z components.
c) Using parts a) and b), what is the total electric field at point P?