A charged particle with charge q enters a region of constant, uniform and mutually orthogonal fields `vecE` and `vecB` with a velocity `vecv` perpendicular to both `vecE` and `vecB`, and comes out without any change in magnitude or direction of `vecv`. Then

Options

A. `vecv=vecBxxvecE//B^(2)`
B. `vecv=vecExxvecB//E^(2)`
C. `vecv=vecBxxvecE//E^(2)`
D. `vecv=vecExxvecB//B^(2)`

Answer

D

Explanation

`vecv=(vecE xx vecB)/(B^(2))`
`rArr v=(EB sin 90^(@))/(B^(2))`
`:. V=(EB)/(B^(2))=(E)/(B)`