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Oscillations

Question
CBSEENPH11026151

Two equal -ve charges -q are fixed at the point (O, a) and (O, a) on the y-axis. A positive charge Q is released from rest at the point (2a, 0) on the x-axis. The charge will :

  • execute SHM about the origin

  • move to the origin and remain at rest

  • move to infinity

  • execute oscillatory but not SHM

Solution

D.

execute oscillatory but not SHM

Component of force on charge +Q at P, along the x-axis,

Fx =2Qq4πεo a2 + x2 cosθ     =2Qq4πεo a2 + x2 × xa2 + x2 Fx  = 2Qqx4πεoa2 + x232

Which is directly proportional to x. So, motion is an oscillatory but not SHM.