JEE Advanced Model Paper 18 with solutions for online practice

A non-conducting disc of radius r and uniform positive surface charge density σ isplaced on the ground, with its axis vertical. A Particle of mass m and charge q is droppedalong the axis of the disc from a height h with zero initial velocity. The ratio of charge tomass of the particle is given by $q/m$ = ${4∊_0g}/σ$