Four point charges are placed at the corners of a square ABCD of side 10 cm, as shown in figure. The force on a charge of `1muC` placed at the centre of square is

Options

A. 7 N
B. 8 N
C. 2 N
D. zero

Answer

D

Explanation

Force of repulsion on `1muC` charge at O due to `3muC` charge, at A and C are equal and opposite. So they cancel each other.
Similarly, force of attraction of `1muC` charge at O due to `-4muC` charges at B and D are also equal and opposite. So they also cancel each other.
Hence the net force on the charge of `1muC` at O is zero.