Charge of +q, +2q, +q and -q are placed at the corners of a square ABCD, calculate the electric field at the intersection of the diagonals of the square when q=5/3×10−9 C and each side square of is 10 cm.
E=k×(q–q+q+2q)r2
=k.3qr2
E=9×109[3×53×10−9](0.1/√2)2
=9000N/C