A neutral particle is at rest in a uniform magnetic field `B`. At time `t = 0` it decays into two charged particles, each of mass `m`.
(a) If the charge of one of the particles is `+q`, what is the charge of the other?
(b) The two particles move off in separate paths, both of them lie in the plane perpendicular to `B`. At a later time, the particles collide. Express the time from decay until collision in terms of `m, B` and `q`.

Answer

[(a) `-q` (b) `(pi m)/(Bq)` ]