Question

Four points charges qa= 2 uc , qb = -5 uc , qc = 2 uc and qd = -5 uc are located at the corners of the square abcd of side 10 cm . what is the force on a charge of 1 uc placed at the centre of the square.

Answer 1

Answer :- Net force on 1μC charge = 0

Explanation :- A rough diagram is shown in figure.
here ABCD is a square in which charges are placed in each corners as shown in figure.
Now, force due to B on 1μC ,$\bold{F_{OB}}$ = Force due to D on 1μC, $\bold{F_{OD}}$
And both act opposite directions so, these forces are cancelled.

Similarly, force due to A on 1μC,$\bold{F_{AO}}$ = force due to C on 1μC, $\bold{F_{CO}}$
and both act opposite directions so, thses forces are also cancelled.
Hence, net force acts on 1μC = 0

Answer 2

Here's the answer. I hope this helps.