A charged particle enters a unifrom magnetic field with velocity vector at an angle of `45^(@)` with the magnetic field . The pitch of the helical path followed by the particles is `rho` . 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)`