Question

Four point charges are placed at the corners of a square a, b, c and d of side 2cm find magnitude and the direction of the electric field at the centre of the square

Answer 1

It actually depends on the charges. If all are of same type and charge then the magnitude of electric field at center of square is zero and direction is undefined.If the electric charges are not of same type,then assume a unit postive charge at the centre of the square and add vectorially each interaction by using the formula E=k*Q/(r^2) where k is 9x(10^9)