Electrostatics 1 Question 11
11. Two equal negative charges $-q$ are fixed at points $(0,-a)$ and $(0, a)$ on $y$-axis. A positive charge $Q$ is released from rest at the point $(2 a, 0)$ on the $x$-axis. The charge $Q$ will $(1984,2 \mathrm{M})$
(a) execute simple harmonic motion about the origin
(b) move to the origin and remain at rest
(c) move to infinity
(d) execute oscillatory but not simple harmonic motion
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Answer:
Correct Answer: 11. (d)
Solution:
- Motion is simple harmonic only if $Q$ is released from a point not very far from the origin on $x$-axis. Otherwise motion is periodic but not simple harmonic.