A ring of mass m and radius r and made of an insulating material carries uniform charge. Initially it rests vertically on a frictionless horizontal tabletop on the left side of the vertical plane AA'. In the region to the right side of AA' is a uniform horizontal magnetic field of induction B pointing everywhere parallel to the axis of the ring. The ring is pushed forward with velocity v but no rotation. If \(q\) is the charge on the ring so that it just starts rolling on the tabletop on entering completely into the magnetic field, what is [200q] in SI units?
details and Assumptions
\(\bullet \) In the given figure cross sign indicates that the field is towards us.
\(\bullet \) neglect induced electric fields.
\(\bullet \) the mass per unit length \(\lambda \)
\(\bullet \) \(\lambda=7 \)
\(\bullet \) \(v=3m/s\)
\(\bullet \) \(B=4T\)