A particle of mass m and charge q moves with a constant velocity v along the positive `x-` direction. It enters a region containing a uniform magnetic field B directed along the negative z direction, extending from `x=a` to `x=b`. The minimum value of v required so that the particle can just enter the region `xgtb` is

Options

A. `(qBb)/m`
B. `(qBa)/m`
C. `(qB(b-a))/m`
D. `(qB(b+a))/(2m)`

Answer

C

Explanation

`(b-a)=` radius of circular part
`=(mv)/(Bq)`
`:. V=(Bq(b-a))/m`