Question

The figure below depict two situations in which two infinitely long static line charges of constant positive line charge density $\lambda$ are kept parallel to each other. In their resulting electric field, point charges $q$ and $-q$ are kept in equilibrium between them. The point charges are confined to move in the $x$ direction only. If they are given a small displacement about their equilibrium positions, then the correct statement(s) is (are)

• A. Both charges execute simple harmonic motion.
• B. Both charges will continue moving in the direction of their displacement.
• C. Charge $+q$ executes simple harmonic motion while charge $-q$ continues moving in the direction of its displacement.
• D. Charge $-q$ executes simple harmonic motion while charge $+q$ continues moving in the direction of its displacement.

Answer 1

The correct option is C Charge $+q$ executes simple harmonic motion while charge $-q$ continues moving in the direction of its displacement.