A particle having charge q and mass m is dropped from a large height from the ground. There exists a uniform horizontal magnetic field B in the entire space as shown in the fig. Assume that the acceleration due to gravity remains constant over the entire height involved.

(a) Argue qualitatively that the particle will touch a maximum depth and then start climbing up. lt brgt (b) Find the speed of the particle at the moment it starts climbing up.
(c) At what depth from the starting point does the par- ticle starts climbing up?

Answer

`(2mg)/(qB) " "(c) h= (2m^(2)g)/(q^(2)B^(2))