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 $q_1$ and $q_3$

Answer 1

The correct option is A shall increase along the positive x-axis

Since positive charge $q_2$ 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 $Q$ ad $(x,0)$ the force on $-q$ shall increase along the positive X-axis.