Question

A ball of mass 100 gm and carrying charge 1 C is released from a point near the surface of earth, in a uniform horizontal magnetic field of 2T. Find the maximum speed attained by the ball in m/s.

Answer 1

Force due to magnetic field = qvB

Force due to gravity = Mg (taking g=10 m/s^2)

now total torque due to forces = mgr + qvB = mv^2/r

put the values to get the answer