Four point charges are placed at the corners of a square with diagonal 2a as shown. What is the total electric field at the center of the square?
kq/a2 at an angle 450 above the +x-axis
kq/a2 at an angle 45o below the -x-axis
3kq/a2 at an angle 45o above the -x-axis
3kq/a2 at an angle 45o below the +x-axis
At center electric field due to both 3q will be canceled. Now net field at center is
E=E1−E2=k2q(a)2−kq(a)2=kq(a)2 This is 45∘ below negative x -axis.