JEE Main 201910 Apr, Morning shiftPhysicsMediumElectrostatics167× since 2002
A uniformly charged ring of radius 3a and total
charge q is placed in xy-plane centred at origin.
A point charge q is moving towards the ring
along the z-axis and has speed u at z = 4a. The
minimum value of u such that it crosses the
origin is :
