Question

Consider two identical positive charges which are fixed on the y- axis, at (0,a) and (0, - a). Let a particle having a negative charge start from the origin O from a point P(x, 0) at a large distance from O, move along the x -axis, passes through O and moves far away from O. Let the acceleration a be taken as positive along its direction of motion. The particle’* acceleration a is plotted against its x - coordinate. Then a vs x curve is given by

Answer 1

Correct option: (d)

Explanation:

The net force F on the particle towards O is the cause of acceleration a .

We observe that F is zero for large values of x and also for x = 0.

So, a must increase to a maximum and fall to zero at O

To the right of O, the net force is to the left while motion is to the right.

Thus, the direction of a is opposite to the particle’* direction of motion and is taken as negative as shown.