ElectrostaticsHard
Question
Two equal negative charges -q each are fixed at the points (0, a) and (0, - a) on the y-axis .A positive charge Q is released from rest at the point (2a, 0) on the x-axis. The charge Q will :
Options
A.Execute simple harmonic motion about the origin
B.At origin velocity of particle is maximum.
C.Move to infinity
D.Execute oscillatory but not simple harmonic motion.
Solution

(i) From diagram, force on Q at general position x, is given by
Fnet = − 2F cos θ = −
(ii) When charge moves from (2a, 0) to origin O, force keeps on acting on Q and becomes zero at O.
∴ Velocity of Q is max. at O.
∴ Velocity of Q is max. at O.
(iii) ∵ Motion is SHM for very small displacements. & 2a is not very small is motion is periodic but not SHM.
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