Question

In figure two positive charges `q_(2)` and `q_(3)` fixed along the y-axis, exert a net electric force in the `+x` direction on a charge `q_(1)` fixed along the x-axis if a positive charge `Q` is added at `(x,0)` the force on `q_(1)`

A. shall increase along the positive x-axis
B. shall decrease along the positive x-axis.
C. shall point along the negative x-axis
D. shall increase but the direction changes because of the intersection of Q with `q_(2)` and `q_(3)`.

Answer 1

Correct Answer - A
The net force on `q_(1)` by `q_(2)` and `q_(3)` is along the +x-direction, so nature of force between `q_(1),q_(2) and q_(1),q_(3)` is attractive. This can be represent by the figure given below.

The attractive force between these charges states that `q_(1)` is a negative charge (since, `q_(2)` and `q_(3)` are positive.)
thus, nature of force between `q_(1)` and newly introduced charge Q (charge) is attractive and net force on `q_(1)` by `q_(2),q_(3)` and Q ar along the same direction as given in the diagram below.

The figure given above clearly shows that the force on `q_(1)` shall increase along the positive x-axis due to the positive charges Q.