A charged particle enters a uniform magnetic field with velocity vector at angle of `45^@` with the magnetic field. The pitch of the helical path followed by the particle is p. the radius of the helix will be

Options

A. `p/(sqrt(2)pi)`
B. `sqrt(2)p`
C. `p/(2pi)`
D. `(sqrt(2)p)/(pi)`

Answer

C

Explanation

`P=(2pimv cos theta)/(qB)=(2pimv)/(sqrt(2)qB)`
`R=(mv sin theta)/(qB)=(mv)/(sqrt(2)qB)=p/(2pi)`