a charged particle having some mass is resting in equlibriumat a height H above the centerof uniformly charged non conducting - Physics - Electric Charges And Fields

Question

a charged particle having some mass is resting in equlibriumat a
height H above the centerof uniformly charged non conducting
horizontal ring of radius R the force of gravity acts downwards the
equilibrium of the particle will be stable
a all values of H
b only for H >R/root2
​c only if H<R/root2
d H= R /root2

Neha Gupta · Accepted Answer

Electric field due to the charged ring is given byE= kQH(H+R)3/2whjere Q is the charge onthe ringlet q is the charge placed at height H
F = qEthis force is equal to mgmg =kQqH(H+R)3/2 (H+R)3/2 = cHwhere c is the constantExact value of H can be calculated  when C is given therefore we can say it is true for all values of H
Hence option (1) is correct