question_answer

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 \[{{q}_{1}}\]:       `                                                                   (NCERT EXEMPLAR)

 

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 \[{{q}_{3}}\]

Correct Answer: A

Solution :

 shall increase along the positive X-axis Since, positive charge \[{{q}_{1}}\] and \[{{q}_{3}}\] exert a net force in the + x-direction on the charge \[{{q}_{1}}\] fixed along the X-axis, the charge \[{{q}_{1}}\] is negative as shown in figure. Obviously, due to addition of positive charge Q at (x, 0), the force on -q shall increase along the positive X-axis.