Question

A particle of the mass ` m ` and cgharge ` 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 minimum value of `v` required so that the particle can just enter the region ` xgtb` is
A. `q b B//m`
B. `q(b -a)B//m`
C. `q a B//m`
D. `q (b+a) B//2m`

Answer 1

Correct Answer - `B`
`r = (mV)/(qB)`
`(b-a) = (mV_(min))/(qB)`
`V_(min) = (q(b-a)B)/(m)`
.