A charged particle enters a magnetic field with the velocity vector making a $45^{\circ}$ magnetic field. If the pitch of the helical path followed by the particle is $\wp$, its radius will be angle with the

Question

$\begin {array} {1 1} (a)\;\large\frac{\wp}{\sqrt 2 \pi} & \quad (b)\;\large\frac{\wp}{ 2 \pi} \\ (c)\;\large\frac{\wp}{ \pi} & \quad (d)\;\large\frac{\sqrt 2\wp}{ \pi} \end {array}$