A charged particle of specific charge s moves undeflected through a region of space containing mutually perpendicular and uniform electric and magnetic fields, E and B. When the field E is switched off, the particle will move in a circular path of radius

Options

A. `E/(Bs)`
B. `(Es)/B`
C. `(Es)/B^2`
D. `E/(B^2s)`

Answer

D

Explanation

`qE=Bqv`
`:. v=E/B` ltbr `r=(mv)/(Bq)=(m(E/B))/(B(q))`
`=E/(B^2S)` (where `S=q/m)`