Question

Two positive charges q and q are placed at the diagonally opposite corners of a square and two negative charges $-$q and $-$q are placed at the other two corners of the square. Then at the centre of the square the resultant electric intensity E and the net electric potential V are

• A. $E\ne 0,V=0$
• B. $E=0,V=0$
• C. $E=0,V\ne 0$
• D. $E\ne 0,V\ne 0$

Answer 1

The correct option is B $E=0,V=0$

See the diagram.
The electric field have same magnitudes for all charges but their directions cancel out. Also the potentials of all charges cancel out as two charges are +q and two charges are -q with r being the same for all charges.