We place four point charges at the vertices ABCD of a square of side a = 1 m, and of of an orthonormal frame OXY of unit vectors and ex 9=9=10-C 92=-29 93 = 29 9₁ = -9 A (91) (92) ey 0 ex (94) D J' (93) C 1. Find the electric field E at the center O of the square. Specify the direction and magnitude of Ē. 2. Express the potential V created at O by the four charges. 3. Express the potential on the parts of the axes xx' and yy' inside the square. What is, in particular, the value of V at the points of intersection of these axes with the sides of the square ( 1.1.1 and 1) ​