Two equal negative charges `-q` are fixed at points `(0, -a)` and `(0,a)` on y-axis. A poistive charge Q is released from rest at point `(2a, 0)` on the x-axis. The charge Q will

Options

A. remain in equilibrium
B. move to infinity
C. perform S.H.M about origin
D. execute oscillatory motion but not S.H.M

Answer

D

Explanation

In the given situation the net electric force from the two charges acts as restoring force for the third charge -Q and hence it will oscillate for sure, but it will not satisfy the condition of S.H.M and hence the oscillation will not be S.H.M. Note that S.H.M is roughly possible only when the displacement given to the charge is negligible.