Four point charges `q_(A)=2 muC, q_(B)=-5 muC, q_(C)=2 muC` and `q_(D)=-5 muC` are located at the corners of square ABCD of side 10 cm. What is the force on a charge of `1 muC` placed at the centre of the square?

Explanation

We can see in the figure that identical charges are placed at diagonally opposite corners of the square. The electric field intensity at the centre becomes zero because the electric field intensity due to one charge is cancelled by the electric field intensity due to the identical charge on the diagonally opposite corner. Therefore, no net force will act on the charged particle at the centre of the square.