Question

Two equal negative charges are fixed at the points [0,a] and [0,a] on y-axis . A positive charge Q is released from rest at the points [2a,0] on the x-axis. The charge Q will

• A. move to infinity
• B. Move to origin and rest there
• C. Undergo SHM about the origin
• D. Execute oscillatory periodic motion but not SHM

Answer 1

The correct option is D Execute oscillatory periodic motion but not SHM

The net force is given as,

$F_n=2Fcos\theta$

$F_n=2\times \frac{1}{4\pi E}\times \frac{-q\times Q}{a^2+x^2}\times \frac{x}{\sqrt{a^2+x^2}}$

Thus, the restoring force is not linear, So, the motion will not be simple harmonic motion but the motion will be oscillatory.