A uniformly charged ring having total charge `Q` and of radius `R` is fixed in such a way so that plane of the ring is horizontal. A charged particle of charge `q` and mass `m` is in equilibrium at any point lying on `y`-axis under the combined forces of electric field and earth's gravitational field. Choose the correct statements

Options

A. If `qQgt0`, particle must be on `+y` -axis
B. If `qQlt0`, particle must be on `-y`-axis
C. If the particle is in stable equilibrium magnitude of `y`-coordinate of particle must be greater than `R/(sqrt(2))`
D. If the particle is at `y` distance from centre of the ring. Specific charge of the particle is `(4iepsilon_(0)(y^(2)+x^(2))^(3/2)g)/(Qy)`

Answer

A, B, C, D

Explanation

`mg=(KQqx)/((y^(2)+x^(2))^(3/2))impliesqm=(4piepsilon_(0)(y^(2)+x^(2))^(3/2)g)/(Qy)`