A beam of protons  with a velocity $4.0\times {10}^5{\text{\hspace{0.17em}ms}}^{\text{-1}}$ enters a uniform magnetic field of 0.2 T at an angle of ${30}^0$ to the magnetic field. If the radius of the helical path taken by the proton beam is  $p\times {10}^{-2}\text{\hspace{0.17em}m}$, then find $p$ (Take $m_{proton}=1.6\times {10}^{-27}kg$)