a). Calculate the magnitude of the electric field at the center of a square 42.5cm on a side if one corner is occupied by a −38.9μC charge and the other three are occupied by −26.9μC charges.


b). Choose the correct direction of the electric field at the center of the square.

perpendicular to the diagonal passing through −38.9μC charge
outward of −38.9μC charge
toward to −38.9μC charge