Q 1.6: Four point charges , , , and are located at the corners of a square ABCD of side 10 cm. What is the force on a charge of 1 μC placed at the centre of the square?
Charges at (A, C) and (B, D) are pairwise diametrically opposite and also equal.
Therefore, their force on a point charge at the centre of the square will be equal but opposite in directions.
Now, AC = BD =
AO = BO = CO = DO = r = Half of diagonal =
Force on point charge at centre due to charges at A and C =
Similarly, Force on point charge at centre due to charges at B and D =
Net force on point charge =
Hence, the charge at the centre experiences no force.