A beam of protons with speed 4 × 10^5 ms^-1 enters a uniform magnetic field of 0.3 T at an angle of 60° to the magnetic field. The pitch of the…

A beam of protons with speed $\displaystyle 4 \times 10^5 \mathrm{~ms}^{-1}$ enters a uniform magnetic field of $\displaystyle 0.3$ T at an angle of $\displaystyle 60$° to the magnetic field. The pitch of the resulting helical path of protons is close to : (Mass of the proton $\displaystyle =1.67 \times 10^{-27} \mathrm{~kg}$, charge of the proton $\displaystyle =1.69 \times 10^{-19} \mathrm{C}$ )